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THIS BOOK
FORMS PART OF THE
ORIGINAL LIBRARY
OF THE
UNIVERSITY OF MICHIGAN
BOUGHT IN EUROPE
1838 TO 1839
BY
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Ε Χ Ρ Ε R Ι Μ Ε Ν Τ S
A N D
OBS ER V A TIONS
ON DIFFERENT KINDS OF
A I R,
&c.
:
1
QUAMOBREM, fi qua eſt erga Creatorem humilitas, fi qua
operum ejus reverentia et magnificatio, fi qua charitas in ho-
mines, fi erga neceſſitates et ærumnas humanas relevandas ſtudi-
um, fi quis amor veritatis in naturalibus, et odium tenebrarum,
et intellectus purificandi deliderium ; orandi ſunt homines iterum
atque iterum, ut, miſlis philoſophiis iftis volaticis et prepofteris,
quæ theſes hypotheſibus antepofuerunt, et experientiam capti-
vam duxerunt, atque de operibus dei triumpharunt, fummiffe,
et cum veneratione quarłam, ad volumen creaturarum evolven-
duni accedant, atque in eo moram faciant, meditentur, et ab
opinionibus abluti et mundi, caſte et integre verſentur. In in-
terpretatione ejus eruenda nulli operæ parcant, fed ftrenue pro-
cedant, perſiſtant, immoriantur.
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E X PER I M E N T S
AND
Ο Β S Ε R V Α Τ Ι Ο Ν 8
A
ON DIFFERENT KINDS OF
ΑΙ
R,
AND OTHER BRANCHES OF
NATURAL PHILOSOPHY, ,
CONNECTED WITII THE SUBJECT.
IN THREE VOLUMES;
Being the former Six Volumes abridged and methodized, with many
Additions,
By JOSEPH PRIESTLEY, LL.D.F.R.S.
AC. IMP. PETROP. R. PARIS. HOLM. TAURIN, ITAL. HARLEM. AUREL.
MED. PARIS. CANTAB. AMERIC. ET PHILAD, SOCIUS.
VOL. I.
Fert animus cauſas tantarum expromere rerum,
Jaimenſumque aperitur opus.
LUCAN.
Motto to the Firſt of tbe Six Volumes.
BIRMINGHA M,
PRINTED BY THOMAS PEARSON;
AND SOLD BY J. JOHNSON, ST. PAUL'S CHURCH-YARD, LONDON.
MDCCXC.
le
*
1
A
Tamster
ܘ ܕ. ܢ ܂ . ܐ
ܕ
то
HIS ROYAL HIGHNESS
GEORGE PRINCE OF WALES,
ud
SIR,
سلام . م کی
IN
N dedicating this work to your ROYAL
Highness, Iexpreſs my own earneſt wiſh,
and that of many others, that to your other
excellent qualities your ROYAL HIGHNESS
may add a diſpoſition to patronize a branch
of ſcience, in the extenſion of which the
natives of Great Britain have ever borne a
diſtinguiſhed part, and which has for its
object the benefit of all mankind.
1
It is by increaſing our knowledge of
nature, and by this alone, that we acquire
the great art of commanding it, of availing
ourſelves of its powers, and applying them
to our own purpoſes ; true ſcience being the
only
A3
vi
DEDICATION. .
1
only foundation of all thoſe arts of life,
whether relating to peace or war, which diſ-
tinguiſh civilized nations from thoſe which
we term barbarous; a diſtinction not leſs
conſpicuous than that between ſome nations
of men and ſome ſpecies of brutes. And
that branch of this great ſcience to which
the ſubject of this work relates, viz. chemiſ-
fry, is perhaps of more various and exten-
ſive uſe, than any other part of natural
knowledge; and by the application that is
now given to it, it is continually growing
in relative magnitude and importance,
In the
age
of Newton chemiſtry was but
little cultivated ; and its value not being
generally known, it was not regularly taught
in places of liberal education, in which na-
tural philofophy was always more or leſs at-
tended to; whereas at preſent every thing
that is not denominated chemiſtry is but a
ſmall part of a ſyſtem of natural knowledge.
It is no leſs remarkable that the doctrine of
air, of which little or nothing was known
in the time of Newton, and which a few
years
DEDICATION.
vii
years ago was hardly mentioned in the writ-
ings of chemiſts, now makes a very con-
ſiderable figure in the maſs of chemical
knowledge, and throws the greateſt light
on the moſt important proceſſes.
It is, therefore, earneſtly to be wiſhed,
that this branch of natural ſcience ſhould
be aſſiduoully cultivated ; and the patronage
of Princes may be eminently uſeful to this
end, by diffuſing a taſte for it among thoſe
whoſe opulence will enable them to pro-
fecute it to the moſt advantage.
It is true that we are indebted to the
poverty of many perſons for ſome of the
moſt ſimple and effectual modes of operat-
ing in chemiſtry; neceſſity having in this,
as well as in many other caſes, been the
happy mother of invention. But in ſome
caſes it is well known that the moſt
pro-
miſing projects have become abortive for
want of the means that were neceſſary to
carry them into execution. For in this
ſcience mere obſervation and reflection will
At
not
viii
DEDICATION.
not carry a man far. He will frequently
have occaſion to put the ſubſtances which
he examines into various new ſituations,
and obſerve the reſult of circumſtances,
which, without expence, as well as labour,
he can have no opportunity of knowing.
Hence it is that the greateſt and happieſt
effects may
be expected from the patronage
of ſcience by perſons of your ROYAL High-
Ness's rank and expectations, whoſe wiſhes
and inclinations are often alone fufficient to
give a turn to the taſte and purſuits of the
rich and great. And hitherto almoſt every
country in Europe can boaſt of more per-
ſons among their nobility, and men of for-
tune, who are devoted to ſcientifical pur-
fuits, than Great Britain.
It will perhaps be ſaid, that men of high
rank and fortune in this country are occu-
pied about the greater objects of civil policy,
and attending to the intereſts and liberties of
the nation. But admitting this to be the
caſe of all, which is evidently that of a
ſmall
5
DEDICATION.
ix
ſmall number only, no one object wholly
engages the attention of any man. All men
have their pleaſures as well as their buſineſs ;
nor is it deſirable that any one object ſhould
ſo much ingroſs any perſon, as that he ſhould
give no degree of attention to any other ;
and no purſuit can have a juſter claim to
the leiſure hours of men of rank and for-
tune than that of natural ſcience ; fince,
independently of any views of utility, none
can furniſh more rational amuſement.
Permit us, then, who are engaged in the
quiet purſuits of philoſophy, to flatter our-
ſelves that they will have the additional re-
commendation of fo effectual a patronage
as that of your ROYAL HIGHNESS; and I am
perfuaded that your Royal HIGHNESS does
not need to be reminded, that the greateſt
princes have been the protectors of ſcience
and of letters, and that they have ever con-
ſidered this patronage as reflecting luſtre on
their crowns.
In
X
DEDICATION.
In ſome countries the ſciences ſeem to
require the ſupport of princes, or of the
community, by penſions and eſtabliſh-
ments. In ours theſe aids are unneceſſary.
Our Royal Society, which gives none but
honorary rewards, is all that is wanted in
the way of eſtabliſhment; and it has been,
and is, eminently uſeful. In this country
patronage is not wanted for thoſe who cul .
tivate the ſciences, but rather for the ſci-
ences themſelves ; to give them their due
value and conſideration, to apply the in-
fluence which the great poſſeſs over the
minds and opinions of men, in directing
their taſtes to uſeful purſuits, and thus to
incite a ſufficient number of able inquirers
to explore the hidden powers which the
Deity has impreſſed on matter.
Conſidering your ROYAL HIGHNESS as
deſtined to be the future ſovereign of this
country, I cannot wiſh you greater glory or
happineſs, than that you ſhould conſider it
as conſiſting, not in the extent, but in the
flouriſh-
DEDICATION.
xi
flouriſhing ſtate, of your dor::inions, to which
ſcience, manufactures, and commerce (each the
true ſource of the other) will moſt eminent-
ly contribute; and that you ſhould not be
dazzled by the flattering, but often fatal,
idea of extending what is called the royal
prerogative; but rather ſtudy to give your
ſubjects every power which they can exer-
ciſe for their own advantage. And what-
ever flatterers may ſuggeſt, the people (each
of them giving his whole attention to thoſe
things in which he is moſt intereſted) will
always be able to do more for themſelves
than the moſt enlightened and beſt diſpoſed
princes can do for them.
As a perſon whoſe deliberate judgment
has led him to diffent from the mode of
religion by law eſtabliſhed in this country,
permit me, Sir, to expreſs ſomething more
than a wiſh, that, as the future ſovereign of
Great Britain you will be the equal father
of all your ſubjects; and that in your reign
every man will meet with encouragement
and favour in proportion to the ſervices he
renders
xii
DEDICATION.
renders his country, and the credit he is
to it.
There has of late years been a wonderful
concurrence of circumſtances tending to ex-
pand the human mind, to ſhew the incon-
venience attending all eſtabliſhments, civil or
religious, formed in times of ignorance, and
to urge the reformation of them. Let theſe
be ſuffered to operate without obſtruction ;
and have the true magnanimity to let no
impediment be thrown in the way of the
efforts of the more enlightened part of the
community to improve the ſtate of it in
any reſpect.
+
u
A ſovereign conducting himſelf by theſe
liberal maxims will rank among the few
truly great and good princes, whoſe object
has not been themſelves, and their perſonal
glory and power, but the real good of their
country; and not that only, or excluſively,
but the benefit of all the human race. А
character thus ſupported will be admired,
and beloved, when that of other princes,
generally,
+
DEDICATION.
xiii
generally, but falſely, called great, will be
conſigned to what is worſe than oblivion,
the deteſtation of all good men.
That your ROYAL Highness may prove
a truly patriot king, an ornament to human
nature, and a bleſſing to your country, and
to mankind, is the fincere wilh, and prayer,
of
Your ROYAL HIGHNESS's,
Moſt obedient
And moſt humble ſervant,
J. PRIESTLEY.
BIRMINGHAM, ?
March 24, 1990.
}
I
T 11 E
P R E F A CE*.
AVING, at different times, publiſhed ſix vo-
lumes of obſervations and experiments re-
lating chiefly to the ſubject of air, and they being
at preſent fo far out of print, that a complete ſet
cannot be had new, it ſeemned more adviſable to
new model the whole work, than reprint the former
volumes.
In ſuch a multiplicity of obſervations, made at
very different times, it could not be but that many
muſt now be fuperfluous; and there muſt alſo be a
variety of imperfections, with which it is not worth
while to trouble the reader. It will alſo be more
agreeable to any perſon who is entering upon theſe
inquiries, to get acquainted with what I have done
in a better method than that in which the particu-
lars happened to occur to myielf, and eſpecially to
** Into this Preface I have introduced every thing that I thought
worth preſerving in the prefaces to all the fix volumes; and it is
hoped that the importance of the obſervations it contains, will be a
ſufficient'apology for the length of it.
fee
+
xvi
THE PREFACE.
ſee all that has been diſcovered with reſpect to any
ſubject of experiment, ſuch as any of the different
kinds of air, &c. with as little mixture of other
matter as poſſible.
Having had a view to ſuch readers, I have en-
deavoured in this new edition to digeſt the contents
of all the ſix volumes, and alſo of thoſe
papers
which, ſince the publication of them, have been
inſerted in the Philoſophical Tranſactions, into fome-
thing like a ſyſtem ; ſome regard, at the ſame time,
being had to the order of time, and of diſcovery, the
better to enable the reader to enter into my views,
and trace the actual progreſs of my thoughts in the
ſeveral inveſtigations.
For the ſake of conciſeneſs, I have not, indeed,
troubled the reader with every conjecture and hypo-
theſis which I formerly adopted; but I have not
failed to mention the moſt conſiderable of them;
not being aſhamed of the miſtakes I have made,
and being willing to encourage young adventurers, by
ſhewing them that, notwithſtanding the many errors
to which even the moſt fagacious, and the moſt cau-
tious, are incident, their labours may be crowned
with conſiderable ſucceſs.
No
+
THE PREFAQE.
xvi
)
: No perſon, I am confident, will now with that,
in order to prevent ſuch miſtakes, I had deferred
the publication of any of my volumes till I had
more nearly completed the courſes of experiments,
of which they contain an account ; and I ſhall ſtill
purſue the ſame method of ſpeedy publication, though
the conſequence of it ſhould be the neceſſity, in
ſome future time, of making another new modelled,
and better purged edition of all my philoſophical
writings.
t
To repeat what I ſaid in the preface of the very
firſt volume of experiments on air ; conſidering the
attention which is now given to this ſubject by phi-
loſophers in all parts of Europe, and the rapid
progreſs that has already been made, and may be
expected to be made, in this branch of knowledge,
all unneceſſary delays in the publication of experi-
ments relating to it, are peculiarly unjuſtifiable.
When, for the ſake of a little more reputation,
men can keep brooding over a new fact, in the dif-
covery of which they might, poſſibly, have very
little real merit, till they think they can aſtoniſh the
world with a ſyſtem as complete as it is new, and give
mankind a high idea of their judgment and penetra-
tion ; they are juſtly puniſhed for their ingratitude
to the fountain of all knowledge, and for their want
VOL. I.
of
2
1
1
1
Xviti
THE PREFACE.
of a genuine love of ſcience and of mankind, in find-
ing their boaſted diſcoveries' anticipated, and the
field of honeſt fame pre-occupied, by.men, who;
from a natural ardour of mind engage in philofophi-
cal purſuits, and with an ingenuous fimplicity im-
mediately communicate to others whatever occurs
to thein in their inquiries.
}
As to myſelf, I find it abſolutely impoſſible to
produce a work on this ſubject that ſhall be any
thing like complete. Every publication I have frankly
acknowledged to be very imperfect, and the pre-
ſent, I am as ready to acknowledge, is ſo. But, ,
paradoxical as it may ſeem, this will ever be the
caſe in the progreſs of natural ſcience, ſo long as
the works of God are, like himſelf, infinite and
inexhauſtible. In completing one diſcovery, we
never fail to get an imperfect knowledge of others, of
which we could have had no idea before; ſo that we
cannot ſolve one doubt without creating ſeveral new
ones.
No philoſophical inveſtigation can be ſaid to be
completed, which leaves any thing unknown that
we are prompted by it to wiſh we could know re-
lating to it. But ſuch is the neceſſary connection
of all things in the ſyſtem of nature, that every dif-
covery bring to our view many things of which we
had
THE PREFACE.
Xix
A
had no intimation before, the complete diſcovery
of which we cannot help wiſhing for ; and when-
ever theſe diſcoveries are completed, we may aſſure
ourſelves they will farther increaſe this kind of dif-
ſatisfaction.
The greater is the circle of light the greater is the
boundary of the darkneſs by which it is confined.
But, notwithſtanding this, the more light we get,
the more thankful we ought to be. For by this
means we have the greater range for ſatisfactory
contemplation. In time the bounds of light will be
ſtill farther extended ; and from the infinity of the
divine nature, and the divine works, we may pro-
miſe ourſelves an endleſs progreſs in our inveſtiga-
tion of them : a proſpect truly ſublime and glorious.
The works of the greateſt and moſt ſucceſsful philo-
ſophers are, on this account, open to our com-
plaints of their being imperfect.
1
1
Travelling on this ground reſembles Pope's de-
ſcription of travelling among the Alps, with this
difference, that here there is not only a ſucceſſion,
but an increaſe of new objects and new difficulties.
So pleas'd at firſt the tow'ring Alps we try,
Mount o'er the vales, and ſeem to tread the ſky.
Th'
XX
THE PRE FAC BI
Th' eternal fnows appear already paſt,
And the firſt clouds and mountains ſeem the laſt.
But thoſe attain'd, we tremble to ſurvey
The growing labours of the lengthen'd way.
Th' increaſing proſpect tires our wand'ring eyes,
Hills peep o'er hills, and Alps on Alps ariſe.
ESSAY ON CRITICISMY
+
Newton, as he had very little knowledge of air,
ſo he had few doubts concerning it. Had Dr.
Hales, after his various and valuable inveſtigations,
given a liſt of all his defiderata, I am confident that
he would not have thought of one in ten that had
occurred to me at the time of my firſt publication;
and my doubts, queries, and hints for new experi-
ments, are very considerably increaſed, after a ſeries
,
of inveſtigations, which have thrown: great light
upon many things of which I was not able to give
any explanation before.
A perſon who means to ſerve the cauſe of ſcience
effectually, muſt hazard his own reputation ſo far as
to riſk even miſtakes in things of leſs moment.
Among a multiplicity of new objects, and new re-
lations, fome will neceſſarily paſs without fufficient
attention ; but if a man be not miſtaken in the prin-
cipal object of his purſuits, he has no occaſion to
diſtreſs himſelf about leſſer things. In the progreſs
of
4
+
--
::
1
..
THE
PREFACE.
xxi
of his inquiries he will generally be able to rectify
his own miſtakes; or if little and envious minds
ſhould take a malignant pleaſure in detecting them
for him, and endeavouring to expoſe him, he is
not worthy of the name of a philoſopher, if he has
not ſtrength of mind ſufficient to enable him not to
be diſturbed at it. He who does not fooliſhly affect
to be above the failings of humanity, will not be
mortified when it is proved that he is but a mai.
I do not think it at all degrading to the buſineſs
of experimental philoſophy, to compare it, as I of-
ten do, to the diverſion of hunting, where it fomc-
times happens that thoſe who have beat the ground
the moſt, and are conſequently the beſt acquainted
with it, weary themſelves without ſtarting any
game; when it may fall in the way of a mere pal-
fenger; ſo that there is but little room for boaſting
in the moſt ſucceſsful termination of the chace.
b
The beſt founded praiſe is that which is due to
the inan, who, from a ſupreme veneration for the
God of nature, takes pleaſure in contemplating his
works, and from a love of his fellow creatures, as the
offspring of the fame all-wiſe and benevolent
parent,
with a grateful ſenſe and perfect enjoyment of the
means of happineſs of which he is already poſſeſſed,
ſeeks, with earneſtneſs, but without murmuring or
2 3
im-
xxii
THE PREFACE.
impatience, that greater command of the powers of
nature, which can only be obtained by a more ex-
tenſive and more accurate knowledge of them ; and
which alone can enable us to avail ourſelves of the
numerous advantages with which we are ſurround-
ed, and contribute to make our common ſituation
more ſecure and happy.
Beſides, the man who believes that there is a go-
vernor as well as a maker of the world (and there is
certainly equal reaſon to believe both) will acknow-
ledge his providence and favour at leaſt as much in
a ſucceſsful purſuit of knowledge, as of wealth; which
is a ſentiment that intirely cuts off all boaſting with
reſpect to ourſelves, and all envy and jealouſy with
reſpect to others; and diſpoſes us mutually to re-
joice in every new light that we receive, through
whoſe hands foever it be conveyed to us.
;
I ſhall paſs for an enthuſiaſt with ſome, but I am
perfectly cafy under the imputation, becauſe I am
happy in thoſe views which ſubject me to it; but
conſidering the amazing improvements in natural
knowledge which haye been made within the laſt
century, and the many ages, abounding with men
who had no other object beſides ſtudy, in which, how-
ever, nothing of this kind was done, there appears to
me to be a very particular providence in the concur-
rence
1
THE PRETACE.
xxiii
rence of thoſe circumſtances which have produced
ſo great a change ; and I cannot help flattering my-
ſelf that this will be inſtrumental in bringing about
other changes in the ſtate of the world, of much
more conſequence to the improvement and hap-
pineſs of it.
This rapid proceſs of knowledge, which, like
the progreſs of a wave of the ſea, of found, or of
light from the ſun, extends itſelf not this way or that
way only, but in all directions, will, I doubt not, .
be the means, under God, of extirpating all error
and prejudice, and of putting an end to all undue
and uſurped authority in the buſineſs of religion, as
well as of ſcience ; and all the efforts of the intereſted
friends of corrupt eſtabliſhments of all kinds, will
be ineffectual for their ſupport in this enlightened
age ; though, by retarding their downfal, they may
make the final ruin of them more complete and
glorious. It was ill policy in Leo X. to patro-
nize polite literature. He was cheriſhing an enemy
in diſguiſe. And the Engliſh hierarchy (if there be
any thing unfound in its conſtitution) has equal rea-
fon to tremble even at an air pump, or an electrical
machine.
.
This is not now a buſineſs of air only, as it was
at the firſt; but appears to be of much greater mag-
a 4
nitude
+
:
XXIV
THE PREFACE,
1
' nitude and extent, ſo as to diffuſe light upon the moſt
general principles of natural knowledge, and eſpeci-
ally thoſe about which chemiſtry is particularly con-
verſant. And it will not now be thought very af-
ſuming to ſay, that, by working in a tub of water,
or a baſon of quickſilver, we may perhaps diſcover
principles of more extenſive influence than even that
of gravity itſelf, the diſcovery of which, in its full
extent, contributed ſo much to immortalize the
name of Newton.
+
I would, however, caution my reader not to be
too ſanguine in his expectations from the happy
train which this branch of philofophy ſeems to be in.
Conſidering the unexampled rapidity with which
diſcoveries have hitherto been made in it, the num-
ber of perſons in many and diſtant countries now en-
gaged in theſe purſuits, and the emulation that is
neceffarily excited in ſuch circumſtances; and con-
ſidering, at the ſame time, how nearly this ſubject
is allied to the moſt general and comprehenſive laws
of nature with which we are acquainted; ſome may
be apt to imagine, that every year muſt produce
diſcoveries equal to all that were made by a New-
ton or a Boyle ; and I am far from ſaying that this
may not be the caſe, or that it is very impro-
bable.
But,
1
THE
PREFACE.
But, though I have little doubt, from the train
that things are viſibly in, that philoſophical diſco-
veries in general will go on with an accelerated pro-
greſs (as indeed they have done ever ſince the re-
vival of letters in Europe) it would be too raſh to
infer, from the preſent flattering appearances, that
any particular expedition into the undiſcovered re-
gions of ſcience will be crowned with more diſtin-
guiſhed ſucceſs than another. Nothing is more
common, in the hiſtory of all the branches of ex-
perimental philoſophy, than the moſt unexpected
revolutions of good or bad ſucceſs. In general, in-
deed, when numbers of ingenious men apply them-
ſelves to one ſubject, that has been well opened,
the inveſtigation proceeds happily and equably.
But, as in the hiſtory of ele&tricity, and now in the
· diſcoveries relating to air, light has burſt out from
the moſt unexpected quarters, in conſequence of
which the greateſt maſters of ſcience have been
obliged to recommence their ſtudies, from new and
ſimpler elements; ſo it is alſo not uncommon for a
branch of ſcience to receive a check, even in the
moſt rapid and promiſing ſtate of its growth.
11
It is true that the rich and the great in this coun-
try give leſs attention to theſe ſubjects than, I be-
lieve, they were ever known to do, ſince the time
of Lord Bacon, and much leſs than men of rank
and
1
1
THE · PREFACE.
1
1
ххүі
and fortune in other countries give to them. But
with us this loſs is made up by men of leiſure, ſpi-
rit, and ingenuity, in the middle ranks of life,
which is a circumſtance that promiſes better for
the continuance of this progreſs in uſeful knowledge
than
any
noble or royal patronage. With us, alſo,
politics chiefly engage the attention of thoſe who
ſtand foremoſt in the community, which, indeed,
ariſes from the freedom and peculiar excellence of
our conſtitution, without which even the ſpirit of
men of letters in general, and of philoſophers in
particular, who never directly interfere in matters of
government, would languilh.
.
It is rather to be regretted, however, that, in
ſuch a number of nobility and gentry, fo very few
ſhould have any taſte for ſcientifical purſuits, becauſe,
for many valuable purpoſes of ſcience, wealth gives
a deciſive advantage. If extenſive and laſting fame
be at all an object, literary, and eſpecially ſcientifical
purſuits, are preferable to political ones in a variety
of reſpects. The former are as much more favour-
able to the diſplay of the human faculties than the
latter, as the ſyſtem of nature is ſuperior to any poli-
tical ſyſtem upon earth.
If extenſive uſefulneſs be the object, ſcience has
the fame advantage over politics. The greateſt
ſucceſs
THE PREFACE.
xxvii
!
ſucceſs in the latter ſeldom extends farther than one
particular country, and one particular age; whereas
a ſucceſsful 'purſuit of ſcience makes a man the
benefactor of all mankind, and of every age. How
trifling is the fame of any ſtateſman that this coun-
try has ever produced to that of Lord Bacon, of
Newton, or of Boyle ; and how much greater are
our obligations to ſuch men as theſe, than to any
other in the whole Biographia Britannica; and every
country, in which ſcience has flouriſhed, can furniſh
inſtances for ſimilar obfervations,
Here my reader will thank me, and the writer
will, I hope, forgive me, if I quote a paſſage from
the poſtſcript of a letter which I formerly re-
ceived from that excellent, and in my opinion,
not too enthuſiaſtical philoſopher, father Beccaria,
of Turin.
1
Mi ſpiace che il mnondo politico, ch' è pur tanto pal-
ſeggero; rubbi il grande Franklin al mondo della natura,
che non ſa ne cambiare, ne mancare. In Engliſh.
“ I am ſorry that the political world, which is ſo
very tranſitory, ſhould take the great Franklin
s from the world of nature, which can never change,
«
or fail.”
Scientifical purſuits have ſuch an advantage over
moſt others, as ought more eſpecially to recommend
them
.
"I
xxvid
THE PRE FACE.
4
them to perſons of rank and fortune. They never
fail to furniſh inaterials for the moſt agreeable and
active purſuits, and ſuch as are, at the ſame time,
in the higheſt degree, uſeful and honourable, and
are, by this means, capable of doing unſpeakably
more for them than the largeſt fortunes can do
without this reſource. Were perſon's thus engaged,
there would be leſs temptation to have recourſe to
pleaſure and diſſipation, for the employment of their
vacant time; and ſuch purſuits would be particu-
larly valuable to thoſe who have no talent for
politics, or any proper call, to occupy themſelves
in public affairs. Beſides, the laſt is a path in
which, from the nature of things, only a very few
can walk; and the former, viz. a courſe of vicious
pleafure, it is much to be lamented that any human
being ſhould tread.
Man is a being endued by his creator with ex-
cellent faculties, and not to have ſerious objects of
purſuit is to debaſe and degrade himſelf. It is to
rank himſelf with beings of a lower order, aiming
at nothing that is much higher than the low plea-
ſures they are capable of; at the ſame time that,
from the remains of nobler powers, of which he
cannot wholly diveſt himſelf, he is incapable of that
unallayed enjoyment of ſenſual pleaſures that brutes
have.
I am
THE PREFACE.
xxix
a
I am ſorry to have occaſion to obſerve, that
natural ſcience is very little, if at all, the object of
education in this country, in which many individuals
have diſtinguiſhed themſelves ſo much by their ap-
plication to it. And I would obſerve that, if we
wiſh to lay a good foundation for a philoſophical
tafte, and philoſophical purſuits, perſons ſhould be
accuſtomed to the ſight of experiments, and prò-
ceſſes, in early life. They ſhould, more eſpecially,
be early initiated in the cheory and practice of in-
veſtigation, by which many of the old diſcoveries
may be made to be really their own; on which
account they will be much more valued by them.
And, in a great variety of articles, very young per-
fons may be made ſo far acquainted with every
thing neceſſary to be previouſly known, as to engage
(which they will do with peculiar alacrity) in pur-
ſuits truly original.
1
.
At all events, however, the curioſity and ſurprize
of young perſons ſhould be excited as ſoon as pof-
ſible; nor ſhould it be much regarded whether
they properly underſtand what they ſee, or not. It
is enough, at the firſt, if ſtriking faćts make an
impreſſion on the mind, and be remembered, We
are, at all ages, but too much in haſte to underſtand,
as we think, the appearances that preſent themſelves
to us. If we could content ourſelves with the bare
knowledge
1
I
+
1
-
XXX
THE PRE FAC É.
knowledge of new fasts, and ſuſpend our judgment
with reſpect to their caufes, till, by their analogy,
we were led to the diſcovery of more facts, of
ſimilar nature, we ſhould be in a much ſurer way
to the attainment of real knowledge.
a
I do not pretend to be perfectly innocent in this
reſpect myſelf; but I think I have as little to re-
proach myſelf with on this head as moſt of
my
brethren ; and whenever I have drawn general con-
clufions too ſoon, I have been very ready to aban-
don them, as all my publications, and this work in
particular, will evidence. I have alſo repeatedly
cautioned my readers, and I cannot too much in-
culcate the caution, that they are to conſider new
fasts only as diſcoveries, and mere dedustions from
thoſe facts, as of no kind of authority; but to draw
all concluſions, and form all hypotheſes, for them-
felves.
I alſo cannot help expreſſing a wiſh that during the
eſtabliſhment of peace in Europe (and happily it is not
in the power of any ſtate to be always at war) we
may fee every obſtruction to the progreſs of know-
ledge, which is equally friendly to all ſtates, re-
moved. Taxes on the importation of books, and
other articles of literature, are ſo impolitic, as well
as illiberal, that it is earneſtly wiſhed that ſomething
may
1
THE PREFACE.
Xxxi
11
may be ſtipulated by contending powers for abo-
liſhing them. There are ſtateſinen whoſe minds
are ſufficiently enlarged to ſee that philoſophy gives
an ample equivalent for the exemption.
I might enlarge much more than I have done
in this preface on the dignity, and utility, of experi-
mental philofophy; but ſhall only obſerve farther,
that it is nothing but a ſuperior knowledge of the
laws of nature, that gives Europeans the advantage
they have over the Hottentots, or the loweſt of our
ſpecies. Had theſe people never known Europeans,
they could not have formed an idea of any mode
of life ſuperior to their own, though it differs but
little from that of the brutes. In like manner,
ſcience advancing, as it does, with an accelerated
progreſs, it may be taken for granted, that man-
kind ſome centuries hence will be as much fuperior
to us in knowledge, and improvements in the arts
of life, as we now are to the Hottentots, though we
cannot have any conception what that knowledge,
or what thoſe improvements, will be. It is enough
for us to ſee that nature is inexhauſtible, that it is
a rich mine, in which we ſhall never dig in 'vain,
and that it is open to infinitely more labourers than
are now employed in exploring its contents, or in
digging for them.
1
Having
Xxxii
THE PREFACE.
Having been a pretty ſucceſsful adventurer in
this great mine, my philoſophical friends in general
wonder that I do not confine my attention to it.
Their diffatisfaction with me is ſo great, and I hear
of it from ſo many quarters, that I think it right to
take ſome opportunity (and a better than the pre-
fent will hardly occur) to make an apology for iny
conduct, eſpecially to thoſe of my friends by whoſe
aſſiſtance I am enabled to give my time to theſe
liberal purſuits ; being pleaſed to think that my
attention to them will be of ſome advantage to
ſcience and the public.
In the firſt place, I would obſerve, that I follow
my own beft judgment in devoting my time to
what I really apprehend to be the moſt important
purſuits, thoſe from which myſelf
, and mankind at
large, will finally derive the greateſt advantage ;
and I muſt be allowed to ſay, that the greater va-
riety of objects to which it is evident that I have
given attention, muſt qualify me to be a better
judge in this caſe than thoſe who cenſure my con-
duct. Perſons who have only one object of purſuit,
never fail to over-rate it, and of courſe to under-
value other things. I would farther obſerve, that
the attention I have given to theology (which, by
the way, is my original and proper province, and
for which I may, therefore, be allowed to have a
juſtifiable
1
1
1
1
THE PRE FACE.
XXXIII
3
juſtifiable predilection) does not engrofs ſo much of
my time as ſome perſons may imagine. I am par-
ticularly complained of at preſent, as having thrown
away ſo much time on the compoſition of my Hif-
tory of the Corruptions of Chriſtianity, of the Opinions
concerning Chriſt, and of the Chriſtian Church in gene-
ral. But I can aſſure them, and the nature of the
thing, if they conſider it, may ſatisfy them, that the
time I muſt neceſſarily have beſtowed upon the
experiments of which an account is contained in
any one of ſix volumes, is much more than I have
given to three or four of thoſe of which the other
conſiſt, and to all the controverſial pieces that I
have written in defence of them. In general, during
the compoſition of thoſe works, the greateſt part of
every day was ſpent in my laboratory, and the
evenings and mornings only in reading or writing.
Beſides, theſe different ſtudies ſo relieve one another,
that I believe I do more in each of them, by ap-
plying to them alternately, than I ſhould do, if I
gave my whole attention to one of them only.
But my principal defence reſts on the ſuperior
dignity and importance of theological ſtudies to any
other whatever, and with ſome obſervations of
this kind I ſhall chuſe to conclude this long Pre-
face.
VOL. I.
b
Every
XXXIV
THE PREFACE
Évery rational being ought to diſtinguiſh, by the
greater attention that he gives to them, thoſe ob-
jects which are of the greateſt importance to him-
felf, and to mankind at large. And certainly, if
there be any juſt rule for eſtimating the value of
à problem, or query, that is propoſed to us, we
muſt think it of infinitely more moment to dif-
cover whether there be a future, and eſpecially an
endleſs, life after this, and how to ſecure a happy
lot in that future life, than to make the beſt
pro-
viſion poſſible for ourſelves in this life, which is
the ultimate object of all natural philoſophy. Stu-
dies, but remotely connected with that great object,
muſt have a dignity and importance infinitely fu-
perior to any other.
A man muſt never have
thought a moment on the ſubject, if he heſitate to
give a decided preference in the caſe. To think or
act otherwiſe, would be li:e'a man buſying him-
ſelf about farthings, who has large eſtates, or king-
doms, depending, and who ſculd negiect the latter
in order to ſecure the former.
All that any philofophical perſon can pretend to
fay in the caſe, muſt be, that the expectation of a
future life is ſo manifeſtly chimerical, that it can
never be worth a wiſe man's while to loſe a moment
in thinking about it, or to employ his time in any
ſtudy relating to it. This I know to be the opi-
nion
THE PREFACE.
XXXY
1
nion of many who will read this book, if not this
prefaçe. But in this I muſt take the liberty to
differ from them, and for reaſons which I ſhall ſub-
mit to their ſerious confideration
1
Natural phenomena, I agree with them, are un-
favourable to any expectation of a future life, and
the doctrine of an immaterial foul, capable of ſub-
fiſting and acting when the body is in the grave
(on which the doctrine of a future ſtate is generally
founded) I am as fully perſuaded as they can be, ·
is unauthorized by any natural appearances what-
ever. My expectation of a future life reſts on an-
other foundation; and, improbable as I acknow-
ledge the doctrine to be, according to the light of
nature, it is nevertheleſs ſuch as I firmly believe,
on the plaineſt of all evidence; the author of nature
having given us an abſolute aſſurance of it, by per-
ſons authorized to ſpeak in his name, and whoſe
divine miſſion was proved by ſuch works as no
other than the author of nature could have enabled
them to perform.
That ſuch works have been performed, and for
this important purpoſe, muſt, I apprehend, bé true,
if there be any truth in hiſtory. And there is no
kind of evidence more eaſily ſubjected to a rigorous
examination than.that which is of the hiſtorical kind,
b 2
the
xxxvi
THE PREFACE.
the maxims of which we are every day converſant
with.
Now it appears to me, that we muſt either ad-
mit the truth of the goſpel hiſtory, which contains
an account of the doctrine, miracles, death, and
reſurrection of Chriſt (on which the belief of a
future life depends) or believe what is infinitely
more incredible, viz. that ſeveral thouſand people,
preſent at the tranſactions, and who had no motive
to believe them without fufficient evidence, but
every motive to turn their eyes from them, or dif-
believe them if they could, ſhould yet, without ſuch
evidence, have given the firmeſt afſent to them,
and have entertained ſo little doubt of the extraor-
dináry facts, as to maintain their faith in them at
the hazard of every thing dear to them in life, and
even chearfully lay down their lives, rather than
abandon their faith. Let philoſophers, as ſuch,
account for this great fast, without admitting more
real iniracles, and thoſe of a more extraordinary
kind, than the belief of chriſtianity requires of me,
and I will relinquiſh my preſent faith, dear as it is
to me, and join them in expoſing it.
As philoſophers, the queſtion between us is, whoſe
faith, ſtrictly ſpeaking, is more agreeable to preſent
appearances. Whatever we may think of an author
of
+
.
1
THE PREFACE.
xxxvii
of nature, and of his attention to it, we equally be-
lieve in the uniforinity of the laws of nature, and that
man, whoſe conſtitution is a part of the ſyſtem of
nature, was the ſame kind of being two thouſand
years ago that he is now; as much as that a horſe
of that age, or an oak tree of that age, had the
ſame properties with the horſes and oaks of the
preſent. Conſequently, whatever was poſſible with
reſpect to man in any former period, is equally poſ-
ſible now,
.
But will any man, who gives a moment's atten-
tion to the ſubject, ſay that it is even poſſible that
ſeveral thouſand perſons, in London or Paris, could
be made to believe that any man in London or
Paris, died and roſe from the dead in their own
life-time, that they ſhould perſiſt in this perſuaſion
through life, without ſhewing any ſign of inſanity,
that they ſhould gain numerous profelytes to their
opinion, though it ſubjected all who embraced it to
all kinds of perſecution, and even to death; and
that the belief of it ſhould eſtabliſh itſelf againſt all
oppoſition, without any perſon being able to detect
the impoſition ?
Now I apprehend that this might take place
more eaſily in London, or in Paris, at this day,
than it could have done at Jeruſalem in the tiine
of
b 3
1
1
Xxxviii
THE PRE FACE.
}
of our Saviour. Human nature could not have
been the fame thing then that we find it to be at
preſent, if mankind could have been ſo impoſed
upon. This I therefore think abſolutely incredible,
and conſequently, as the leſs difficulty of the two,
as believing a thing much leſs improbable, I admit
the truth of the goſpel hiſtory, the admiſſion of
which makes the ſubſequent account of the pro-
pagation of chriſtianity (which all hiſtory, and even
the preſent ſtate of things, proves to be true) per-
fectly eaſy and natural. Admitting theſe leading
facts, all the reſt follows of courſe, and all things
came to be as they are without any farther miracle.
But real miracles we muſt have ſomewhere, in or-
der to account for the preſent ſtate of things;
and if we muſt admit miracles, let them be ſuch
as have a great object, and not ſuch as have no
object at all, but only ſerve to puzzle and con.
1
1
found us.
The hiſtory of the Jews, and the books of the
Old Teſtament, furniſh many facts, which no hy-
potheſis beſides that of the divine origin of their
religion can explain. Let the philoſopher only
admit as a poſtulatum that Jews are, and always
were, men, conſtituted as other men are, and let
him not deceive himſelf, by conſidering them as be-
ings of another ſpecies. All I with in this reſpect
I
is,
THE PREFACE.
xxxix
is, that perſons who pretend to the character of phi-
lofophers, would be ſo throughout, and carry the .
ſame ſpirit into the ſtudy of hiſtory, and of human
nature, that they do into their laboratories; firſt af-
ſuring themſelves, with reſpect to fasts, and then ex-
plaining thoſe facts by reducing them to general prin-
ciples (which, from the uniformity of nature, muſt
be univerſally true) and then I ſhall have no doubt
of their becoming as firm believers in chriſtianity aş
myſelf. They will find no other hypotheſis, that
can explain ſuch appearances as they cannot deny to
be real. Let philoſophers now ſay, whether there
be reaſon in this, or not.
I therefore take the liberty, having been led to
advance thus much, to addreſs my brother philoſo-
phers on a ſubject equally intereſting to us as philofo-
phers, and as men. Do not diſregard a queſtion of
infinite moment. Give it that degree of attention
to which it is naturally intitled ; and eſpecially do
not ſo far abandon the ſerious character of philofo-
phers, as to laugh where you ought to reafor. At
leaft, do this great ſubject, and yourſelves, the juſ-
tice to conſider the facts, and endeavour to frame
fome hypotheſis by which to account for them; and
do not decide in half an hour, on an inquiry which
well deſerves the ſtudy of a great part
of
your
lives.
I,
b 4
if
THE PRE FACE.
$
If I have a ſtronger bias than many other perſons
in favour of chriſtianity, it is that which philoſophy
gives me. I view with rapture the glorious face of
nature, and I admire its wonderful conſtitution, the
laws of which are daily unfolding themſelves to our
view. It is but little that the life of man permits
us to ſee at preſent, and therefore I feel a moſt
eager
deſire to renew my acquaintance with it hereafter,
and to reſume thoſe inquiries with which I am ſo
much delighted now, and which muſt be interrupt-
ed by death.
Could I imagine that the knowledge of nature
would ever be exhauſted, and that we were ap-
proaching to a termination of our enquiries, I could
more contentedly ſhut my eyes on a ſcene in which
nothing more was to be ſeen, or done. But to quit
the ſtage at preſent (and I believe the aſpect of
things will be exactly ſimilar in any future period of
our exiſtence) without the hope of re-viſiting it,
would fill me with the deepeſt regret. The general
who, like Epaminondas, or Wolfe, dies in the arms
of victory, dies with ſatisfaction ; but not ſo he that
is cut off in the beginning of a doubtful, though
promiſing, engagement. Thus I feel on the idea
of ceaſing to breathe, when I have but juſt begun to
know what it is that I breathe.
:
4
5
M. Her
t
1
THE PRE FACE.
xli
M. Herſchell's late diſcoveries in, and beyond,
the bounds of the ſolar ſyſtem, the great views that
he has given us of the arrangement of the ſtars,
their revolutions, and thoſe of the immenſe ſyſtems
into which they are formed, are peculiarly calcu-
lated to inſpire an ardent deſire of ſeeing ſo great a
ſcene a little more unfolded. Such diſcoveries as
theſe, give us a higher idea of the value of our being,
by raiſing our ideas of the ſyſtem of which we are
apart, and, with this, an earneſt wiſh for the conti-
nuance of it.
1
Beſides, civil ſociety is but in its infancy, the world
itſelf is but very imperfectly known to the civilized
inhabitants of it, and we are but little acquainted
with the real value of thoſe few of its productions
of which we have ſome knowledge, and which we
are only beginning to name, and to arrange. How
muſt a citizen of the world wiſh to know the future
progreſs of it?
To have no wiſh of this kind certainly argues a
low, an ignoble, and I will ſay, an unphiloſophical
mind. I conſider all ſuch perſons, how ſuperior
r.
ſoever they may be to myſelf in other reſpects, with
pity and concern. They would have unſpeakably
more fatisfaction in their philoſophical purſuits, if
they carried them on with the views of things that
I have
xlii
PREFACE,
THE
I have. It has been juſtly obſerved, that great
views indicate, and indeed conſtitute, great minds.
What elevation of mind, then, would the pro-
ſpects of the chriſtian, add to thoſe of the philofo-
pher !*
+
With men of reflection this apology for my con-
duct will, I doubt not, be admitted as ſatisfactory;
and till I hear better reaſons than have yet been of-
fered to me for changing my conduct, I ſhall con-
tinue to give my attention to my different purſuits,
according to my own ideas of their reſpective im-
portance ; and my friends have no reaſon to fear
that I ſhall neglect philoſophy. It has, perhaps, but
too ſtrong charms for me.
I ſhall endeavour, how-
ever, to keep it in its proper place, and not fo
1
* If any of my philoſophical friends Mould be induced, by what
I have bere urged, to look into my theological writings, I would
take the liberty to recommend to them my Letters to a Philoſophical
Unbeliever, the Inſtitutes of natural and revealed Religion, the Genc.
ral Hiſtory of the Chriſtian Church, till the Fall of the Weſtern Empire,
and the Hiſtory of the Corruptions of Chriſtianity, eſpecially the Con-
clufion, Part I. relating to Mr. GIBBON, who has declined engaging
in the diſcuſſion I there propoſed to him. If they wish to ſee more
particularly in what manner chriſtianity came to be encumbered
with the doctrine of the trinity, which has been the foundation of
one of the greateſt objections to it, I would further refer them to
my Hiſtory of early Opinions concerning Chriſt, where they will ſee it
traced to its proper fource in the Platonic philofophy, and where
it is proved that the primitive chriſtian church was unqueſtionably
unitarian.
much
3
1
+
THE PREFACE.
xliii
1
much attach myſelf to the ſtudy of the laws which
govern this world, as to loſe ſight of the ſubſerviency
of this world, and of all things in it, to another and
a better ; in which I hope to reſume theſe pleaſing
philoſophical purſuits, and to ſee, in a comprehen-
five view, thoſe detached diſcoveries which we are
now making here.
adjuſt them.
At preſent all our ſyſtems are in a remarkable man-
ner unhinged by the diſcovery of a multiplicity of
fakts, to which it appears difficult, or impoſſible, to
We need not, however, give our-
ſelves much concern on this account.
For when a
ſufficient number of new facts ſhall be diſcovered
(towards which even imperfect hypotheſes will con-
tribute) a more general theory will ſoon preſent it-
ſelf; and perhaps to the moſt incurious and leaſt
ſagacious eye. Thus, when able navigators have,
with great labour and judgment, ſteered towards
an undiſcovered country, a common failor, placed
at the maſt head, may happen to get the firſt ſight
of the land. Let us not, however, contend about
mnerit, but let us all be intent on forwarding the
common enterprize, and equally enjoy any progreſs
we may make towards ſucceeding in it ; and above
all, let us acknowledge the guidance of that Great
Being, who has put a ſpirit in man, and whoſe inſpira-
tion giveth bim underſtanding.
I have
xliv
THE PREFACE.
I have not, in this edition, given a ſummary riera
of facts, ſuch as I gave in the fifth of the preceding
volumes, partly becauſe I found it would have made
the laſt volume of a diſproportionate ſize, but chiefly
becauſe the arrangement of the preſent work, and
the Index to the whole, rendered it leſs neceſſary.
Such a ſummary will be found in Mr. Keir's Che-
mical Dictionary, and in Elementary Treatiſes,
comprizing what all experimenters on air have dif-
covered.
As I wiſh to preſerve the memory of my patrons
(though I hope to do in a more effectual manner
than this. I would obſerve that the ſix original volumes
were inſcribed to the following perſons; viz. the Mar-
quis of Lanſdown, Sir George Savile, the late Earl of
Stanhope, Sir John Pringle, Doctor Heberden, and
William Conſtable, Eſq. of Burton Conſtable.
.
CON
1
C Ο Ν Τ Ε Ν Τ S
1
OE
THE
F IS T
V O L U M E.
1
THE
HE Introduction
page
1
Sect. I. A general View of preceding Diſcoveries re-
lating to Air
ibid.
Sect. II. Of the Uſe of Ternis
8
Sect. III. An Account of the Apparatus with which
the following Experiments were made
12
1
Β Ο Ο Κ I.
OBSERVATIONS AND EXPERIMENTS RE-
LATING TO FIXED AIR
43
PART
I.
Of the Relation of fixed Air to Water
ibid.
Sect. I. Of the Impregnation of Water with fixed
ibid.
Sect. II. Of the State of Air in Water
56
PART
xlvi
CONTENTS
PART
II.
63
Of the Subſtances which yield fixed Air chiefly by
Heat
Sect. I. Of Air extraEted from Mineral Sub-
ſtances
ibid.
Sect. II. Air from faline Subſtances
81
Sect. III. Air from Subſtances of a vegetable Ori-
gin
Sect. IV. Air from Animal Subſtances
94
87
II2
PART III.
Various Properties of fixed Air
100
Sect. I. 'The Effeats of fixed Air on Animals and
Vegetables
ibid.
Sect. II. Of the Change snade in fixed Air by the
electric Spark
Sect. III. Miſcellaneous Obſervations on the Proper-
ties of fixed Air
119
1. The Acidity of fixed Air
ibid.
2. Fixed Air expelled from IVater by boiling 120
3. The freezing of Water impregnated with fixed
ibid.
4. Fixed air, how affeeted by Iron Filings and
Sulphur
I 21
5. Iron
!
CONTENTS. xlvii
122
ter
5. Tron in fixed Air
6. Fixed Air changed by Incorporation with Wa-
123
7. Fixed Air expoſed to Heat
125
8. A Source of Deception from fixed Air, contained
in Water
ibid.
9. Of fixed Air in acetous Fermentation 126
10. Fixed Air from putrefying animal Subſtances
127
PART IV.
Of the conſtituent Principles of fixed Air 129
Sect. I. Fixed Air contains Water
ibid.
Sect. II. Fixed Air may be procured by Means of
nitrous Acid
133
Sect. III. Fixed Air may be formed by Means of
Something imbibed
from the Atmoſphere 136
Sect. IV. Of the Generation of fixed Air from the
vitriolic Acid
I 42
Sect. V. Of the Compoſition of fixed Air from-dephlo-
giſticated Air, and Phlogiſton, by the Generation of
it from heating together Subſtances containing each
145
Sect. VI. Of the Generation of fixed Air, by heating
Subſtances containing Phlogiſton in dephlogiſticated
159
Sect.
of them
xlviii
CO N T E N T S.
I
Sect. VII. Of the Produktion of fixed Air by beat-
ing Subſtances containing dephlogiſticated Air in in-
flammable Air
167
Sect. VIII. Of Air afting through a Bladder
174
В оок
II.
EXPERIMENTS AND OBSERVATIONS RE-
LATING TO INFLAMMABLE AIR 182
PART I.
Experiments and Obſervations relating to the Pro-
, duction of inflammable Air
ibid.
Sect. I. Of inflammable Air from Metals, by Means
of Acids, &c.
ibid.
Sect. II. Of inflammable Air from Oil
195
Sect. III. Of the Production of inflammable Air from
different Subſtances, by Means of Heat and Wa-
+
ter
200
Sect. IV. Of Air produced by Subſtances putrefying
in Water
206
Sect. V. Of Air produced by various Subſtances pul-
trefying in Quickſilver
216,
PART II.
Of the Properties of inflammable Air
223
Sect.
CONTENT S.
xlix
1
Sect. I. Various Experiments to change and decom-
poſe inflammable Air
223
1. Inflanımable Air diminiſhed by Charcoal
ibid.
2. Of Putrefačtion in inflammable Air
224
3. Plants growing in inflammable Air ibid.
4. Water impregnated with inflammable Air 225
5. Inflammable Air agitated in Oil of Turpen-
tine
228
6. Animals dying in inflammable Air 229
7. Inflammable Air changed by keeping in Wa-
230
8. The elettric Spark in inflammable Air
232
9. The Smell of inflammable Air
ibid.
Sect. II. Inflammable Air decompoſed by Heat, in
Tubes of Flint Glaſs
234
Sect. III. Of ſulphurated inflammable Air 241
Sect. IV. Metals, and other Subſtances containing
Phlogiſton, formed by imbibing inflammable Air 248
ter
2
PART III.
Of the Conſtitution of inflammable Air
266
Sect. I. Experiments which prove that Water is a
necefſary Ingredient in inflammable Air ibid.
VOL. I.
C
Sect.
1
1
I
CONTENT S.
Sect. II. Inflammable Air from Charcoal and Iron,
&c. by Means of Steam
280
Sect. III. Of the Aetion of Steam on various Sub-
ſtances in a red Heat
301
Sect. IV. Whether inflammable or nitrous Air con-
tain more Phlogiſton
304
Sect. V. . The Analyſis of different kinds of inflam-
mable Air
308
Β Ο Ο Κ
III.
A
EXPERIMENTS
AND OBSERVATIONS RE-
LATING TO NITROUS AIR.
328
PART I.
Of the Source of nitrous Air
ibid.
Sect. I. Of nitrous Air from Metals
ibid.
Sect. II. Of nitrous Air from Vapour of Spirit of
Nitre and Water
335
Sect. III. Of the increaſed Produce of nitrous
Air, by previouſly converting the Acid into Va-
pour
341
Sect. IV. Of the Produktion of nitrous Air by Means
of phlogiſticated nitrous Acid
347
Sect. V. Of Air from Gunpowder
351
PART
.
CON TEN T S.
li
PART U.
Of the Properties of nitrous Air
351
Sect. I. Of nitrous Air as the Test of the Purity of
reſpirable Air
ibid.
Sect. II. Of the Impregnaticn of Water with ni-
trous Air
364
Sect. III. Of the Abſorption of nitrous Air by Oils,
Spirit of Wine, and cauſtic Alkali
372
Sect. IV. Of the Phenomena cttending the Abforptionz
of nitrous Air by Acid Liquors
381.
Sect. V. Of the antiſeptic Power of nitrous' air
391
Sect. VI. Of the Formation of nitrous Ammoniac by
nitrous Air
398
Sect. VII. Explanation of fome Phenomena attending
the Solution of Metals in nitrous Acid
402
Sect. VIII. Miſcellaneous Properties of nitrous
Air
407
1. Of the freezing of Water impregnated with ni-
trous Air
ibid.
2. Of the burning of a Mixture of nitrous and in-
flammable Air
3. Of Plants and Animals in nitrous Air
409
4. Of the Uſe of nitrous Air in Clyfters
410
408
1
1
!
Τ Η Σ
INTRODUCTION.
SECTION 1.
d general view of PRECEDING DISCOVERIES relating
to air
OR the better underſtanding of the experi-
ments and obſervations on different kinds of
air contained in this treatiſe, it will be uſeful to
thoſe who are not acquainted with the hiſtory of this
branch of natural philoſophy, to be informed of
thoſe facts which had been diſcovered by others,
before I turned my thoughts to the ſubject ; which
ſuggeſted, and by the help of which I was enabled
to purſue, my enquiries. Let it be obſerved, how-
ever, that I do not profeſs to recite in this place all
that had been diſcovered concerning air, but only'
thoſe diſcoveries the knowledge of which is necef-
ſary, in order to underſtand what I have done my-
ſelf; fo that any perſon who is only acquainted with
the general principles of natural philoſophy, may
Vol. I,
B
be
1
2
Set. 1.
THE INTRODUCTION.
be able to read this trcatifes and, with proper. at-
tention, to underſtand every part of it.
That the air which conſtitutes the atmoſphere in
which we live has weight, and that it is elaſtic, or
conſiſts of a compreſſible and dilatable fluid, were
ſome of the earlieſt diſcoveries that were made af-
ter the dawning of philoſophy in this weſtern part
of the world.
Alſo Van Helmont, and other chymiſts who ſuc-
ceeded him, were acquainted with the property of
ſome vapours to ſuffocate, and extinguiſh flame,
and of others to be ignited ; effects, indeed, which
could not but have been known in all ages. But they
had no idea that the ſubſtances (if, indeed, they
knew that they were ſubſtances, and not merely pro-
perties, and effections of bodies which produced thoſe
effects) were capable of being ſeparately exhibited
in the form of a permanently elaſtic vapour, not con-
denſable by cold, to which I give the name of air,
any more than the thing that conſtitutes finell.
In fact, they knew nothing at all of any air beſides
common air, and therefore they applied the term to
no other ſubſtance whatever.
That elaſtic fluids, differing effentially from the
air of the atinoſphere, but'agreeing with it in the
properties of weight, elaſticity, and transparency,
might be generated from folid ſubſtances, was dif-
covered by Mr. Boyle, through two remarkable
4
kinds
SeEt. 1
3
THE INTRODUCTION,"
1
kinds of factitious air, at leaſt the effects of them,
had been known long before to all miners. One
of theſe is heavier than common air. It lies at the
bottom of pits, extinguiſhes candles, and kills ani-
mals that breathe it, on which account it had ob-
tained the name of the choke damp. The other is
lighter than common air, taking its place near the
roofs of ſubterraneous places; and becauſe it is
liable to take fire, and explode, like gunpowder, it
had been called the fire damp. The word damp ſig-
nifies vapour or exhalation in the German and Saxon
language.
Mr. Boyle was, I believe, the firſt who diſcover-
ed that what we now call fixed air, and alſo inflam-
mable air, are really elaſtic fluids, capable of being
exhibited in a ſtate unmixed with common air, a
fact which nothing that was known before his time
could have given him the leaſt reaſon to expect;
nor, in fact, did he make the diſcovery by any kind
of reaſoning a priori. It was the unexpected reſult
of his experiments.
Though the former of theſe kinds of air had been
known to be noxious, the latter, I believe, had not
been diſcovered to be ſo; having always been found,
in its natural ſtate, ſo much diluted with common
air, as to be breathed with ſafety. Air of the for-
mer kind, beſides having been diſcovered in various
caverns, particularly the grotta del Cane in Italy,
B 2
had
1
+
Seet, I.
THE INTRODUCTION,
-
had alſo been obſerved on the ſurface of fermenting
liquors, and had been called gas (which is the ſame
with geist, or ſpirit) by Van Helmont, and other
German chymiſts ; but afterwards it obtained the
name of fixed air, eſpecially after it had been dif-
covered by Dr. Black of Edinburgh to exiſt
, in a
fixed ſtate, in alkaline ſalts, chalk, and other cal-
careous ſubſtances.
This excellent philoſopher diſcovered that it is the
preſence of the fixed air in theſe ſubſtances that
renders them snild, and that when they are deprived
of it, by the force of fire, or any other proceſs,
they are in that ſtate which had been called cauſtic,
from their corroding or burning animal and veget-
able ſubſtances.
Fixed air had been diſcovered by Dr. Macbride
of Dublin, after an obſervation of Sir John Prin-
gle's, which led to it, to be in a conſiderable de-
gree antiſeptic; and ſince it is extracted in great
plenty from fermenting vegetables, he had recom-
mended the uſe of wort (that is an infuſion of malt
in water) as what would probably give relief in the
ſea-ſcurvy, which is ſaid to be a putrid diſeaſe.
Dr. Brownrigg had alſo diſcovered that the ſame
ſpecies of air is contained in great quantities in the
water of the Pyrmont ſpring at Spa in Germany,
and in other mineral waters, which have what is
called an acidulous taſte, and that their peculiar
flavour,
1
Sez. I,
5
THE INTRODUCTION.
flavour, briſkneſs, and medicinal virtues, are de-
rived from this ingredient.
Dr. Hales, without ſeeming to imagine that there
was any material difference between theſe kinds of
air and common air, obſerved that certain ſub-
ſtances and operations generate air, and others ab-
forb it ; imagining that the diminution of air was
ſimply a taking away from the common maſs, with-
out any alteration in the properties of what remained.
His experiments, however, are ſo numerous, and
various, that they are juſtly eſteemed to be the ſolid
foundation of all our knowledge of this ſubject.
Mr. Cavendiſh had exactly aſcertained the ſpecific
gravities of fixed and inflammable air, ſhewing the
former of them to be it heavier than common
air, and the latter ten times lighter. He alſo ſhew-
ed that water would imbibe more than its own bulk
of fixed air.
Laſtly, Mr. Lane diſcovered that water thus im-
pregnated with fixed air will diffolve a conſiderable
quantity of iron, and thereby become a ſtrong cha-
lybeate.
Beſides theſe two kinds of factitious air, that
which I call nitrous air obtruded itſelf upon Dr.
Hales; but even he, as I obſerved, had no idea of
there being more than one kind of air, loaded with
different vapours; and was far from imagining that
they differed from one another ſo very effentially as
they
B 3
4
11
6
Seet. T.
THE INTRODUCTION.
they are now known to do. And though Mr.
Boyle, Dr. Hales, and others, could not but be ac-
quainted with the effuvium of ſpirit of ſalt, and alſo
of volatile alkali, they could have no idea that the
ſubſtance which had thoſe powers was capable of
being ſeparated from common air, and of being ex-
hibited free from moiſture, in the form of a perma-
nently elaſtic vapour, to appearance exactly like that
which conſtitutes the common atmoſphere. Or if
any perſon, till within theſe very few years, had ſuch a
notion (of which, however, I do not believe that
they have given the leaſt intimation) it muſt
have been a mere random conjecture, and what no-
thing but actual experiment could have aſcertained.
Even Mr. Cavendiſh, whoſe experiments relating
to air immediately preceded my own, appears not
to have had ſo much as a ſuſpicion of this kind.
For he relates an experiment of his, on the ſolution
of copper in the marine acid, as inexplicable, ex-
cept on the hypotheſis of there being a kind of air
that loſt its elaſticity by the contact of water, which ad-
mits of the eaſieſt ſolution imaginable, on the fup-
poſition of the ſpirit of ſalt emitting a vapour,
which though capable of being confined by quick-
ſilver, and of being by that means exhibited in the
form of air, was inſtantly abſorbed by water, which
would thereupon become poſſeſſed of all the proper-
ties of common ſpirit of ſalt,
In
t
"
Geet. T.
7
THE INTRODUCTION.
".
In fact, none of the chymiſts appear to have had
the leaſt idea of its being even poſſible to ſeparate
the acid or alkaline principles from the water with
which they are always found combined; and there-
fore, though they did ſuppoſe them capable of far-
ther concentration, they ſtill conſidered a certain por-
tion of water, as abſolutely eſſential to them; and
conſequently all the experiments that have hitherto
been made on the affinities of the acids, and alkalis,
are, in fact, nothing more than the affinities of con-
pound ſubſtances, conſiſting of the acids or alkali,
and water.
The above-mentioned, I would obſerve, are by
no means all the diſcoveries concerning air that
have been made by the gentlemen whoſe names I
have mentioned, and ſtill leſs are they all that have
been inade by others; but they comprize all the
previous knowledge of this ſubject that is neceſſary
to the underſtanding of this treatiſe ; except a few
particulars, which will be mentioned in the courſe
of the work, and which it is, therefore, unneceſſary
to recite in this place.
6
.
:
i
В 4
SEC-
t
8
Seet, II,
THE INTRODUCTION, .
7
SECTION II.
,
Of the Uſe of Terms.
IN
N writing on the ſubject of different kinds of
air, I found myſelf at a loſs for proper terms, by
which to diſtinguiſh them, thoſe which have him
therto obtained being by no means ſufficiently cha-
racteriſtic, or diſtinct. The only terms in common
uſe were, fixed air, mephitic, and inflammable. The
laſt, indeed, ſufficiently characterizes and diſtin-
guiſhes that kind of air which takes fire, and ex-
plodes on the approach of Aame ; but it might have
been termed fixed with as much propriety as that to
which Dr. Black, and others before him, had given
that denomination; ſince it is originally part of ſome
ſolid ſubſtance, and exiſts in an unelaſtic ſtate.
The term mephitic is equally applicable to what
is called fixed air, to that which is inflammable, and
to many other kinds ; ſince they are equally noxi-
ous, when breathed by animals. Rather, however,
than either introduce new terms, or change the
fignification of old ones, I have uſed the term fixed
air, in the ſenſe in which it is now commonly uſed,
and have diſtinguiſhed the other kinds by their pro-
perties, or ſome other periphraſis. I have been under
a ne-
Sect. II.
9
THE INTRODUCTION.
a neceſſity, however, of giving names to thoſe kinds
of air, to which no names had been given by others,
as nitrous, acid, alkaline, &c.
No perſon was ever more temperate, or more
cautious, than I have been in the introduction of
new terms, conſidering the number of new facts
that I have diſcovered. It was with great heſitation,
though compelled by neceſſity, that I did it at all ;
generally with the advice of my moſt judicious
friends, and always adopting ſuch as were analogous
to others in, eſtabliſhed uſe. Thus when I found ·
the terms common or atmoſpherical air, fixed air, and
inflammable air, uſed by all philoſophers, and no
perſon whatever had objected to them, it was cer-
tainly natural for me to continue to apply the term
air to other elaſtic tranſparent fluids, not condenſable
by cold, and to diſtinguiſh them by other appella-
tions, drawn from the peculiar circumſtances of
their production, as nitrous air, acid air, alkaline
air, phlogiſticated and dephlogiſticated' air, &c. uſing
the term air as expreſſive of the mere form in which
a ſubſtance is exhibited, without any conſideration
of the elements of which it conſiſts. I therefore
think the term gas, which many uſe, in this ſenſe,
to be unneceſſary; the term air, as it had long
been uſed by philoſophers, being ſufficient for the
purpoſes
They
!
1
IO
Seet, II.
THE
INTRODUCTION.
1
They who chuſe to apply the term air to a ſub-
ſtance, and not to a form, are certainly at full li-
berty ſo to do, if they pleaſe; and provided we
underſtand one another, no inconvenience will re-
ſult from our uſe of a different language. But
then the ſame perſons ſhould be uniform in their ab-
jections and practice, and call nothing by the name
of air that they do not believe to conſiſt of that one
elementary ſubſtance to which they profeſs to appro-
priate the term. The language that I adopt, in
this reſpect, implies no attachment to any hypo-
theſis whatever, and may ſtill be uſed though I
ſhould change iny opinion on that ſubject; which
is certainly a very great advantage in philoſophical
language. In adopting the terms phlogiſticated and
dephlogiſticated air, I did not, I own, uſe the ſame
judgment; but as by good fortune, they do not
appear at all improper, I do not ſee any ſufficient
reaſon to abandon them. The azote in the new no-
menclature is not expreſſive of any thing peculiar to
what I have called phlogiſticated air ; and the term
vital, does not ſufficiently diſtinguiſh dephlogiſti-
cated from conmon, or atmoſpherical air,
Some perſons more particularly object to the
term air, as applied to acid, alkaline, and even nie
trous air ; but it is certainly very convenient to have
a common term by which to denote things which
have
1
i
1
1
/
SeEZ. 11.
THE INTRODUCTION.
11
have ſo many common properties, and thoſe fo very
Itriking ; all of them agreeing with the air in which
we breathe, and with fixed air, in elaſticity, and tranf-
parency, and in being alike affected by heat or cold;
ſo that to the eye they appear to have no difference
at all. With much more reaſon, as it appears to
me, might a perſon object to the common term
metal, as applied to things fo øery cäfferent from
one another as gold, quickſilver, and lead.
Beſides, acid and alkaline air do not differ from
common air (in any reſpect that can countenance
an objection to their having a common appellation)
except in ſuch properties as are common to it with
fixed air, though in a different degree; viz. that of
being imbibed by water. But, indeed, all kinds of
air, common air itſelf not excepted, are capable of
being imbibed by water in ſome degree.
Some may think the terms acid and alkaline va-
pour more proper than acid and alkaline air. But
the term vapour having always been applied to
elaſtic matters capable of being condenſed in the
temperature of the atmoſphere, eſpecially the va-
pour of water, it ſeems harſh to apply it to any
elaſtic ſubſtance, which at the ſame time that it is as
tranſparent as the air we breathe, is no more affect-
ed by cold than it is.
SEC-
1
IL
Seet. III.
THE INTRODUCTION.
SECTION III.
N
An account of the APPARATUS with which the following
experiments were made.
RA
U
ATHER than deſcribe at large the manner
in which every particular experiment that I
ſhall have occaſion to recite was made, which would
both be very tedious, and require an unneceſſary
multiplicity of drawings, I think it more adviſeable
to give, at one view, an account of all my appara-
tus and inſtruments, or at leaſt of every thing that
can require a deſcription, and of all the dif-
ferent operations and proceſſes in which I employ
them.
It will be ſeen that my apparatus for experiments
on air is, in fact, nothing more than that of Dr.
Hales, Dr. Brownrigg, and Mr. Cavendiſh, diver-
ſified, and made a little more ſimple.
For experiments in which air will bear to be con-
fined by water, I firſt uſed an oblong trough made
of earthern ware, as a Plate I. fig. 1. about eigh
inches deep, at one end of which I put thin filat
ſtones, about an inch, or half an inch, under
the water, uſing more or fewer of them according to
the quantity of water in the trough. I afterwards found
it more convenient to uſe a larger wooden trough,
of
Sect. III.
13
THE INTRODUCTION.
of the ſame form, with a ſhelf about an inch lower
than the top, inſtead of the flat ſtones above-men-
tioned. But I now uſe a trough, two feet two
inches long, one · foot two inches widey and nine
inches 'deep, for common purpoſes, and others of
different dimenſions for particular uſes. In making
them the joints are fixed in freſh paint, which renders
them perfectly water tight.
In one end of this trough are ledges, on which it
can ſlide, ſo that I can take it out with pleaſure; I
have alſo a ſhelf like Fig. 1. Plate III. except that it
is not ſuſpended, as that is, by thin pieces of copper,
bended into the form of hooks, which, however,
anſwered very well. The ſhelf is about an inch
and an half in thickneſs, for the convenience of ex-
cavating the under-ſide in the form of funnels, the
orifices of which, about a quarter of an inch in
diameter, appear on the 'upper fide, as the form
and ſize of the cavity below is expreſſed by the
dots above. This was an ingenious contrivance of
the Duc de Chaulnes.
Theſe funnels ſhould be made as capacious as por-
ſible ; but care ſhould more eſpecially be taken, that
no part of them be too flat, leſt any bubbles of air
ſhould be retained, and not paſs into the veſſels
placed to receive them,
When freſh air is generated, it is convenient to
introduce the tube of the phial in which it is pro-
duced, quite under the ſhelf, into the hollow of
the
:
1
14
Sect. III.
THE INTRODUCTION,
1
the funnel. But when it happens that the ſweep of
the tube is to ſhort for that purpoſe, I make uſe of
a ſmall production of the upper part of the ſhelf,
with a ſit in it, under which the ſhorter tube may
be brought ; and the edge of the jar that receives
the air, may be made to ſlide over the place at
which the bubbles iflue:
Fig. 2. Plate III. is a ſide view of a glaſs funnel
ſupported by a wooden pillar, riſing from a baſe,
to which a plate of lead is faſtened, in order to
make it ſink, and keep its place in the water. At
the top of the pillar is a piece of wood cut in front
(but, for that reaſon, not viſible in this figure) in a
concave form, for ſupporting a glaſs tube, that,
reſting on the orifice of the funnel, may lean againſt
it. Both this piece of wood, and alſo that which
ſupports the funnel, are made to Nide
up
and down,
and are fixed by wedges at whatever height is found
to be moſt convenient. This apparatus ſaves the
trouble and inconvenience of keeping one's hand in
the water for the ſake of holding the funnel, while
the air is pouring through it.
Fig. 3. Pl. III. repreſents an apparatus that
would not deſerve a copper-plate, but that there is
often great convenience in little things. It exhibits
a baſon of water, or quickſilver, fo placed, in a frame
of wood, as to contain ſeveral glaſs tubes, which
may be ſupported with little trouble, and diſpoſed of
without materially interfering with each other. In
this
1
Sect. III.
15
THE INTRODUCTION.
-
this manner I have often more than half a dozen
in uſe at the ſame time.
After uſing this baſon for quickſilver, which, on
many accounts, is, in general, more convenient
than
any
other form of a reſervoir. I found I had
liad occaſion to transfer air from one jar to another
in quickſilver, in the fame manner as I had uſed to
do in water; and then I found it abſolutely necef-
ſary for this purpoſe, to make uſe of an oblong
trough, Pl. V. fig. 1. That which I have com-
monly uſed is made of wood, feven inches long,
three wide, and three deep, made cylindrical at the
bottom, in order to make the leaſt quantity of
of quickſilver neceſſary. But I have an upright
piece of wood at one end, contrived to ſupport
tall glaſs veſſels without danger of falling. It is
only with ſuch an apparatus as this, that given
quantities of alkaline and acid airs can be mixed, as
is deſcribed in the courſe of the work.
The ſeveral kinds of air I uſually keep in cylin-
drical jars, as c, c, Pl. I. fig. 1, about ten inches
long, and two and an half wide, being ſuch as I have
generally uſed for electrical batteries ; but I have
likewiſe veſſels of very different forins and ſizes,
adapted to particular experiments.
When I want to remove veſſels of air from the
large trough, I place them in pots or diſhes, of va-
rious ſizes, to hold more or leſs water, according
to the time that I have occaſion to keep the air, as
fig.
1
1
:
16
SeEt. III.
THE
INTRODUCTION.
fig. 2. Theſe I plunge in water, and ſide the jars into
them; after which they may be taken out together,
and be ſet wherever it ſhall be moſt convenient.
For the purpoſe of merely removing a jar of air
from one place to another, where it is not to ſtand
longer than a few days, I make uſe of common
tea-diſhes, which will hold water enough for that.
time, unleſs the air be in a ſtate of diminution, by
means of any proceſs that is going on in it.
If I want to try whether an animal will live in
any kind of air, I firſt put the air into a ſmall vef-
ſel, juſt large enough to give it room to ſtretch it-
ſelf; and as I generally make uſe of mice for this
purpoſe, I have found it very convenient to uſe the
hollow part of a tall beer-glaſs, d Fig. 1, which
contains between two and three ounce meaſures of
air. In this veſſel a mouſe will live twenty minutes,
or half an hour.
For the purpoſe of theſe experiments it is moſt con-
venient to catch the mice in ſmall wire traps, out of
which it is eaſy to take them, and, holding them, by
the back of the neck, to paſs them through the
water into the veſſel which contains the air. If I
expect that the mouſe will live a conſiderable time,
I take care to put into the veſſel ſomething on
which it may conveniently ſit, out of the reach of
the water. If the air be good, the mouſe will
foon be perfectly at its eaſe, having ſuffered no-
thing by its paſſing through the water. If the
3
air
1
t
Sect. III.
17
THE INTRODUCTION.
1
1
air be ſuppoſed to be noxious, it will be proper (if
the
operator be deſirous of preſerving the mice for
farther uſe) to keep hold of their tails, that they
may be withdrawn as ſoon as they begin to ſhew
ſigns of uneaſineſs ; but if the air be thoroughly
noxious, and the mouſe happens to get a full in-
ſpiration, it will be impoſſible to do this before it be
abſolutely irrecoverable.
In order to keep the mice, I put them into re-
ceivers open at the top and bottom, ſtanding upon
plates of tin perforated with many holes, and co-
vered with other plates of the ſame kind, held
down by ſufficient weights, as Pl. I. fig. 3. Theſe re-
ceivers ſtand upon a frame of wood, that the freſh
air may have an opportunity of getting to the bot-
toms of them, and circulating through them. In
the inſide I put a quantity of paper or tow, which
muſt be changed, and the veſſel waſhed and dried,
every two or three days. This is moft conveniently
done by having another receiver, ready cleaned and
prepared, into which the mice may be transferred
till the other ſhall be cleaned.
Mice muſt be kept in a pretty exact temperature,
for either much heat or much cold kills them prefently.
The place in which I have generally kept them,
was a ſhelf over the kitchen fire-place, where, as
it is uſual in Yorkſhire, the fire never goes out ;
to
that the heat varies very little, and I find it to be,
с
VOL. I.
at
18
Sez. IIT.
THE INTRODUCTION.
!
+
at a medium, about 70 degrees of Fahrenheit's
thermometer. When they had been made to paſs
through the water, as they neceſſarily muſt be in
order to a change of air, they require, and will bear,
a very conſiderable degree of heat, to warm and
dry them.
N.B. I found, to my great ſurprize, in the courſe of
theſe experiments, that mice will live intirely with-
out water ; for though I have kept them for three
or four months, and have offered them water ſeveral
times, they would never taſte it ; and yet they con-
tinued in perfect health and vigour. Two or three
of them will live very peaceably together in the ſame
veſſel; though I had one inſtance of a mouſe tearing
another almoſt in pieces, and when there was plenty
of proviſions for both of them.
In the ſame manner in which a mouſe is put into
a veſſel of any kind of air, a plant, or any thing
put
into it, viz. by paſſing it through
the water; and if the plant be of a kind that will
grow in water only, there will be no occaſion to ſet
it in a pot of earth, which will otherwiſe be neceſſary.
There may appear, at firſt ſight, fome difficulty
in opening the mouth of a phial, containing any
ſubſtance, ſolid or liquid, to which water muſt not
be admitted, in a jar of any kind of air, which is
an operation that I have ſometimes had recourſe to ;
but this I eaſily effect by means of a cork cut tapering,
and
elfe, may
be
!
1
SeEt. 111:
THE INTRODUCTION.
19
into it again
and a ſtrong wire thruſt through it, as in fig. 4, for
in this form it will ſufficiently fit the mouth of any
phial, and by holding the phial in one hand, and
the wire in the other, and plunging both my hands
in the trough of water, I can eaſily convey the phial
through the water into the jar, which muſt either
be held by an aſſiſtant, or be faſtened by ſtrings,
with its mouth projecting over the ſhelf. When the
phịal is thus conveyed into the jar, the cork may
eaſily be removed, and may alſo be
put
at pleaſure, and conveyed the ſame way out again.,
When any thing, as a gallipot, &c. is to be ſup-
ported at a conſiderable height within ajar, it is con-
venient to have ſuch wire ſtands as are repreſented fig.
5. They anſwer better than any other, becauſe they
take up but little room, and may be eaſily bended to
any ſhape or height:
If I have occaſion to pour air from a veſſel with
a wide mouth into another with a very narrow one,
I am obliged to make uſe of a fumel, fig. 6, but
by this means the operation is exceedingly eaſy; firſt
filling the veſſel into which the air is to be conveyed
with water, and holding the mouth of it, together
with the funnel, both under water with one hand,
while the other is employed in pouring the air ;
which, aſcending through the funnel up into the vef-
fel, makes the water deſcend, and takes its place.
Theſe funnels are beſt made of glaſs, becauſe the air
being viſible through them, the quantity of it may
be
C 2
1
10
Šešt. III.
THE INTRODUCTION.
be more eaſily eſtimated by the èýě. It will be
convenient to have ſeveral of theſe funnels of different
lizes.
In order to expel ait from ſolid ſubſtances by
means of heat, I ſometimes put them into a gun-
barrel, Pl. II. fig. 7, and filling it up with dry land,
that has been well burned, ſo that no air can come
from it, I lute to the open end the ſtem of a tobacco
pipe, or a ſmall glaſs čubė. Then hâving put' tlië
cloſed end of the barrel, which contains the mate-
rials, into the fire, the generated air, iſſuing through
the tube, may be received in a veſel of quick-
ſilver; with its mouth immerſed in ä baſon of tlie
fame, ſuſpended all together by wires in the manner
deſcribed in the figure, or teſting on a ſolid ſupport:
any other fuid ſubſtance inay be uſed inſtead of
quickſilver.
But the moſt accurate iñethod of procuring air
from ſeveral ſubſtances; by means of heat, is to put
them, if they will bear it; into phials, ſuch as a, a, á,
Pl. IV. full of quickſilver, with their móütlis iñ-.
merſed in the ſame, and theñ throwing the focus
of a burning mirror upon them. For this purpoſe
the phials ſhould be made with their bottoms round,
and very thin, that they may not be liable to break
with a pretty ſudden application of heat.
If I want to expel air from any liquid; I nearly
fill a phial with it, and having á cork perforated, I
put through it, and ſecure with cement, a glaſs
tube
}
$
Sect. III.
21
THE INTRODUCTION.
tube, bended in the manner repreſented at e Pl. I. fig. I.
I then put the phial into a kettle of water, which I ſet
upon the fire and make to boil. The air expelled
by the heat, from the liquor contained in the phial,
iſſues through the tube, and is received in a baſon
of quickſilver. Inſtead of this ſuſpended baſon,
I ſometimes content myſelf with tying a flac-
cid bladder to the end of the tube, in both theſe pro-
ceſſes, that it may receive the newly generated air. .
I would obſerve, with reſpect to this proceſs,
and every other in which veſſels are to be filled
with quickſilver, and then to be placed inverted in
baſons of the fame, that no operation is eaſier (un,
leſs the mouth of the veſſel be exceedingly wide)
when the mouth of it is covered with ſoft leather,
and, if neceſſary, tied on with a ſtring, before it be
turned upſide down ; and the leather may be drawn
from under it when it is plunged in the quickſilver.
If the mouths of the yeffels be very narrow, it will
be fufficient, and, moſt convenient, to cover them
with the end of one's finger.
But if the air, diſengaged from any ſubſtance,
will be attracted by mercury, as is the caſe with all
thoſe which contain the nitrous acid, this proceſs
cannot be uſed, and recourſe muſt be had to the
vacuum ; and for this purpoſe it is neceſſary that
the operator be provided with receivers made very
thin, on purpoſe for theſe experiments. Such as
1
C3
are
I
22
THE INTRODUCTIONSez. IfT.
.
.
are commonly uſed for other experiments are much
too thick for this purpoſe, being very liable to break
with the application of the heat produced by the
burning lens. In this proceſs, care ſhould be taken
to place the materials on glaſs, a piece of crucible,
or ſome other ſubſtance that is known to yield no
air by heat. ?
The figure, b Pl. IV.repreſents a common glaſs phial
with a ground ſtopper, with inany ſmall holes in it,
which was a happy contrivance of my ingenious pupil
and friend Mr. Benjamin Vaughan. It is of excellent
uſe to convey any liquid, or even any kind of air,
contained in it, through the water, into a jar ſtand-
"ing with its mouth inverted in it, without admitting
any mixture of the common air, or even of the
water; and yet the air generated within it has a
fufficient out-let. Theſe phials will be found uſe
ful in a great variety of experiments.
The figure c, repreſents a phial of the ſame forin
with a; but the neck is thicker, in order to be fitted
with a ground ſtopper, perforated, and drawn out
into a tube, to be uſed inſtead of the phiale,
Pl. I. Till I hit upon this contrivance, which
was executed for me by the direction of Mr. Parker,
I had a great deal of trouble in perforating common
corks, bending and fitțing tubes to them; and, after
all, the corks themſelves, or the cement, with which
I generally found it convenient to cover the ends of
the
F
1
Sect. III.
23
THE INTRODUCTION.
1
the tubes, were apt to give way, and to be the occa-
ſion of very diſagreeable accidents. Beſides, if any
hot acid was uſed, the vapour would corrode the
cork, and an allowance was to be made for the
effect of that circumſtance on the air: whereas, with
this
apparatus, which is exceedingly convenient and
elegant, the operator may be ſure that nothing but
glaſs is contiguous to the materials he works
upon,
as he can perfectly exclude every other foreign in-
fluence; and while it remains unbroken, it is never
out of repair, or unfit for uſe.
For many purpoſes, however, the former method,
with corks and tubes, will be found very fufficient,
and much leſs expenſive; eſpecially with the fluor
acid, which corrodes glaſs, and which will preſently
eat through one of theſe delicate phials. For this
purpoſe, therefore, I would recommend the uſe of
a common and very thick phial, eſpecially as no
great degree of heat, and never any ſudden applica-
tion of heat, is wanted.
The phial c, will be found ſufficient for any pur-
poſe that does not require more heat than the flame
of a candle held cloſe to the bottom of it, can ſup-
ply; but if there be occaſion to place the phial in a
fand-heat, and conſequently if it muſt be put into a
crucible placed on the fire, it will be neceſſary to
have the tube, in which the ground ſtopper termi-
nates, made as long as may be, as repreſented by e;
other-
1
C 4
24
Sect. III.
THE INTRODUCTION.
otherwiſe the veſſels that receive the air will be too
near the fire. Nine or twelve inches, however, will
be a ſufficient length for any purpoſe.
I have great reaſon to congratulate myſelf on this
apparatus, having found it to be of moſt admirable
uſe. For, in experiments with air, where the great-
eſt poſſible accuracy is required, lutes are by no
means to be truſted, ſince a variety of vapours,
coming into contact with them, are conſiderably
affected; whereas theſe ſtoppers being ground air-
tight, the operator may be perfectly at eaſe, both
with reſpect to the quantity and the quality of his
produce. To expreſs this proceſs as conciſely as
poſible, I generally allude to it, by ſaying that the
phials have ground ſtoppers and tubes.
In experiments in which it is not worth while to
be at the expence of theſe phials with ground ſtop-
pers and tubes, and yet where gun-barrels cannot,
be truſted to, on account of the materials corroding
the iron, I haye recourſe to a kind of long phial, or
a tube made narrower at the open end, nine or
twelve inches in length, and of an equal thickneſs
throughout, repreſented Pl. IV.fig. d. When theſe
phials are put into a crucible with fand, the bottom
may be made red-hot, while the top is ſo cool, that a
cominon cork (into which a glaſs tube is inſerted)
tvill not be affected by the heat. In fact, this veſſel
is a kind of a gun-barrel made of glaſs, and is uſed
3
exactly
!
1
A
Set. III.
25
THE INTRODUCTION.
#
i
exactly like the gun-barrel; except that it is not ex-
poſed to fo great a degree of heat.
When the materials are put into this veffe!, it
muſt be filled up to the mouth with fine fand, that
will give no air by the application of heat, and the
cork muſt be thruſt down cloſe upon the land,
The air muſt be received as in plate 2. fig. 7,
Theſe glaſs veſſels, however, will not bear a great
degree of heat, and therefore by applying to Mr.
Wedgwood (who is as great, and generous a friend
of ſcience, as he is diſtinguiſhed by the wonderful
improvements he has made on his own beautiful art.)
I got earthen tubes and retorts, which will bear any
degree of heat, and being glazed, or not, as the ocor
caſion requires, I have found them of the moſt
extenſive uſe in my experiments.
When a perſon has a great many trials to make
of the goodneſs of air, it is of no ſmall importance
to have contrivances by which he may ſave time.
Having, particularly, had frequent occaſion to mea-
ſure the purity of air by means of nitrous air, in
which it is ſometimes neceſſary to put ſeveral mea-
ſures of one kind to one meaſure of the other; and
being wearied with taking all the meaſures ſeparate-
ly, at length I hit upon the very uſeful expedient
of having the meaſures ready made, conſiſting of
veſſels, the capacities of which had a known pro-
portion to each other, as f, f, f, Pl. IV. each veſel
holding twise as much as the ſize next leſs than it,
I found
1
!
1
A
26
Seei. II
THE INTRODUCTION
+
I found it likewiſe convenient to liave the veſſels in
which the mixture of air is made, fig. g, marked in
à manner-correſponding to theſe phials, that the
diminution of the air may be perceived at once,
without the application of any meaſure. If one of
theſe phials contain an ounce-meaſure, and the reſt
be multiplies and ſubdiviſions of it, it will be ſtill
more convenient.
- There is a great variety of methods of mixing
nitrous and common air, in order to aſcertain the
purity of the latter. But the manner in which I
have now long been accuſtomed to perform that
operation is ſtill more ſimple, though it has nothing
to boaſt of with reſpect to ingenuity. It is necef-
fary. to deſcribe it, becauſe it is referred to through
the greater part of this work.
I firſt provide a phial, containing about an ounce
of water, which I call the air meaſure. This I fill
with air by having firſt filled it with water, and placed
it over the opening of the funnel in my ſhelf; and
when it is filled I ſlide it along the ſhelf, always
obſerving that there be a little more air than I want.
The phial. being thus exactly filled with the air
which I am about to examine, and care being taken
that it be 'not warmed by holding in the hand, &c.
I empty it into a jar about an inch and an half in
diameter, and then introduce to it the ſame meaſure
of nitrous air, and let them continue together about
two minutes... I chuſe: to have an overplus of
nitrous
:
4
Seft. TIT.
27
THE INTRODUCTION.
.
nitrous air, that I may be ſure to have phloģiſton
enough to faturate all the common air. "If I find
the diminution with theſe imeaſures to be very con-
fiderable, I introduce another meaſure of nitrous air;
but the pureſt dephlogiſticated air will not; I believe,
require more than two equal meaſures of nitrous air.
Sometimes I leave the common and nitrous air
in the jar all night, or a whole day ;-- but always
take care that, whatever kinds of air 'I be comparing
together, they remain the fame-ſpace of time be-
fore I proceed to note the degree of diminution.
If the two kinds of air be agitated on coming into
contact with each other, the diminution will be
much greater; and therefore this circumſtance
ſhould always be expreſſed.
When the preceding part of the proceſs is overy
I transfer the air into a glaſs tube, about two feet
long, and one third of an inch wide, carefully gra-
duated according to the air-meaſure, and divided
into tenths and hundred parts; ſo that one of the
latter will be about a fixth or an eighth of an inch.
Then immerſing the tube in a trough of water, ſo
that the water in the inſide of the tube ſhall be on a
level with the water on the outſide, I obſerve the
ſpace occupied by them both, and expreſs the reſult
in meaſures, and decimal parts of a meaſure, accord-
ing to the graduation of the tube.
It is ſome trouble to graduate a tube in this man-
ger; but when it is once done, the application of it
is
28 THE INTRODUCTION. Sect. III.
is extremely eaſy. As it will ſeldom happen that
a glaſs tube is of an equal diameter throughout, I
generally fill that paſt of the tube which contains
one meaſure, with quickſilver, and then weighing it,
and dividing it into ten parts, put them in ſeparately,
in order to mark the primary diviſions. This
operation is performed very readily by having a
glaſs tube drawn out to a fine orifice, in order to
take up a ſmall quantity of quickſilver at a time,
as it may be wanted.
Meaſuring the purity of reſpirable air, I mix with
it an equal quantity of nitrous air, or if it be
highly dephlogiſticated, two equal quantities of
nitroys air, which is always particularly mentioned
in the courſe of this work: after this I transfer the
mixture into a graduated tube. Conſequently a leſs
number in the reſult is always an indication of greater
purity. This number, in order to be as conciſe as
poſſible, I have in this work termed the meaſure of
the teſt, or the ſtandard of the air. Thus, if when
I mix two equal quantities of common air and
nitrouş air, they afterwards accupy the ſpace of one
meaſure, and two tenths of a meaſure, I fay the
meaſures of the teſt were 1. 2. or the ſtandard of the
air was I. 2.
If the quantity of the air, the goodneſs of which
I wanted to aſcertain, was exceedingly ſmall, ſo as
to be contained in a part of a glaſs tube, out of
which water will not run fpontaneouſly, I for-
merly
-
Sect. III. THE INTRODUCTION. 29
merly had recourſe to the following method ; I
firſt meaſured with a pair of compaſſes the length of
the column of air in the tube, the remaining párt
being filled with water, and laid it down upon a
ſcale ; and then, thruſting a wire of a proper thick-
neſs, into the tube, I contrived, by means of a
thin plate of iron, bent to a ſharp angle, to draw it
out again, when the whole of this little apparatus
was introduced through the water into a jar of nitrous
air; and the wire being drawn out, the air from the
jar muſt ſupply its place. I then meaſured the
length of this column of nitrous air which I had got
into the tube, and laid it alſo down upon the ſcale,
ſo as to know the exact length of both the columns.
After this, holding the tube under water, with a
ſmall wire I forced the two ſeparate columns of air
into contact; and when they have been a ſufficient
time together, I meaſured the length of the whole,
and compared it with the length of both the columns
taken before But I now have tubes, made
very ſmall for this purpoſe, and a longer tube,
graduated in proportion, which I uſe as I do the
larger veſſels when the quantity of air is fuf-
ficient.
In experiments on thoſe kinds of air which are
teadily imbibed by water, I often make uſe of quick-
lilver, in the manner repreſented Pl. II. fig. 8, in
which a is the baſon of quickfilýer, b a glaſs veſiel
con-
.
30
Sect. III.
THE INTRODUCTION,
containing quickſilver, with its mouth immerſed in
it, ç a phial containing the ingredients from which
the air is to be produced, and d is a ſmall recipient,
or glaſs veſel deſigned to receive and intercept any,
liquor that may be diſcharged along with the air,
which is to be tranſmitted free from
any
moiſture
into the yeffel b. If there be no apprehenſion of
moiſture, I make uſe of the glaſs tube only, without
any recipient, in the manner repreſented e Pl. I.
In order to invert the veffel b; I firſt fill it with
quickſilver, and-then carefully cover the mouth of
it with a piece of ſoft leather; after which it may
be turned upſide down without any danger of ad-
mitting the air, and the leather may be withdrawn
when it is plunged in the quickſilver.
In order to generate air by the ſolution of metals,
or any proceſs of a ſimilar nature, I put the materials
into a phial, prepared in the manner repreſented at e
Pl. I. and put the end of the glaſs tube under the
mouth of any veſſel into which I want to convey
the air. If heat be neceſſary I can eaſily apply to
it a candle, or a red hot poker while it hangs in
this poſition.
When I have occaſion to transfer air from a jar
ſtanding in the trough of water to a veſſel ſtanding
in quickſilver, or in any other ſituation whatever,
I make uſe of the contrivance repreſented P1. Il fig. 9,
which conſiſts of a bladder, furniſhed at one end
with
1
Sect. III.
32
THE INTRODUCTION.
with a ſinall glaſs tube bended, and at the other
with a cork, perforated ſo as juſt to admit the ſmall
end of a funnel. When the common air is care-
fully preſſed out of this bladder, and the funnel is
thruſt tightly into the cork, it may be filled with
any kind of air as eaſily as a glaſs jar; and then a
ſtring being tied above the cork in which the funnel
is inſerted, and the orifice in the other cork clofed,
by preſſing the bladder againſt it, it may be carried
to any plate, and if the tube be carefully wiped, the
air may be conveyed quite free from noiſture
through a body of quickſilver, or any thing elſe.
A little practice will make this very uſeful mancuvre
perfectly eaſy and accurate. But I find it more
convenient to have a ſmall braſs cock, to thruſt into
the cork, through which the air is introduced into
the bladder.
In order to impregnate fluids with any kind of
air, as water with fixed air, I fill a phial with the
fluid, larger or leſs as I have occaſion (as a Pl.Jl fig. 10)
and then, inverting it, place it with its mouth down-
.wards, in a bowl b, containing a quantity of the ſame
fluid; and having filled the bladder, fig. 9, with
the air, I throw as much of it as I think proper
into the phial, in the manner deſcribed above. To
accelerate the impregnation, I lay my hand on the
top of the phial, and ſhake it as much as I think
Proper.
If,
32
Sest. TIT.
THE INTRODUCTION.
1
If, without having any air previouſly generated,
I would convey it into the fuid immediately as it
ariſes from the proper materials, I keep the ſame
bladder in connexion with a phial c fig. 10, con-
taining the ſame materials (as chalk, ſalt of tartar, or
pearl afhes in diluted oil of vitriol, for the genera-
tion of fixed air) and taking care (leſt, in the act of
efferveſcence, any of the materials in the phiala
ſhould get into the veſſel á) to place this phial on
á ſtand lower than that on which the baſon was
placed, I preſs out the newly generated air, and
make it aſcend directly into the fluid. For this
purpoſe, and that I may more conveniently ſhake
the phial t, which is neceſſary in ſome proceſſes,
eſpecially with chalk and oil of vitriol, I foiñetimes
make uſe of a flexible leathern tube d, and ſome-
times only a glaſs tube. For if the bladder be of
a ſufficient length, it will give room for the agita-
tion of the phial; or if not; it is eaſy to connect
two blådders together by means of a perforated
cork, to which they may both be faſtened.
When I want to try whether any kind of air
will admir a candle to burn in it, I make uſe of a
cylindrical glaſs veſſel, Pl. I. fig. 11, and a bit of wax
candle a fig. 12, faſtened to the end of a wire b,
and turned up, in ſuch a manner as to be let down
into the veſſel with the flame upwards. The veſſel
ſhould be kept carefully covered till the moment
that
Seet, IIT:
33
THE INTRODUCTION.
that the candle is admitted. In this manner I have
frequently extinguiſhed a candle more than twenty
times ſucceſſively, in a veſſel of this kind, though
it is impoſſible to dip the candle into it without
giving the external air an opportunity of mixing
with the air in the inſide more or leſs. The cans
dle at the other end of the wire is very conveni-
ent for holding under a jar ſtanding in water, in
order to burn as long as the incloſed air can ſupply
it; for the moment that it is extinguiſhed, it may
be drawn through the water, before any ſmoke can
have mixed with the air.
In order to draw air out of a veffel which has
its mouth immerſed in water, and thereby to raiſe
the water to whatever height may be neceſſary, it
is very convenient to make uſe of a glaſs ſyphoni,
putting one of the legs up into the veiſel, and
drawing the air out at the other end by the
mouth. If the air be of a noxious quality, it may
be neceffary to have a ſyringe faſtened to the ſyphon,
the manner of which needs no explanation. I have
not thought it fate to depend upon a valve at the
top of the vefiel, which Dr. Hales ſometimes
made uſe of.
If, however, a very ſmall hole be made at the top
of a glaſs veijel, it may be filled to any height by
holding it under water, while the air is iſvingout at the
hole, which may then be cloſed withi wax or cement.
Vol. I.
D
If
34
Seet. HIT.
THE INTRODUCTION.
t
If the generated air will neither be abſorded by
water, nor diminiſh common air, it may be con-
venient to put part of the materials into a cup,
ſupported by a ſtand, and the other part into a
ſmall glafs veffel, placed on the edge of it, as at
f Pl. I. fig. 1. Then having, by means of a fyphon,
drawn the air to a convenient height, the ſmall
glaſs veffel may be caſily puſhed into the cup, by
a wire introduced through the water; or it may
be contrived, in a variety of ways, to diſ-
charge the contents of the finall veſſel into the
larger. The diſtance between the boundary of air
and water, before and after the operation, will ſhew
the quantity of the generated air. The effect of
proceſſes that diminiſh air may alſo be tried by the
fame apparatus.
When I want to admit a particular kind of air
to any thing that will not bear wetting, and yet
cannot be conveniently put into a phial, and eſpe-
cially if it be in the form of a powder, and muſt
be placed upon a ſtand (as in thoſe experiments
in which the focus of a burning mirror is to be
thrown upon it) I firſt exhauſt a receiver, in which
it is previouſly placed; and having a glaſs tubę,
bended for the purpoſe, as in Pl. II. fig. 14, I
fcrew it to the ſtem of a transfer of the air-pump
on which the l'ecciver had been exhauſted, and
--- introducing it through the water into a jar of that
kind
Sei, II.
35
THE INTRODUCTION:
kind of air with which I would fill the receiver,
I only turn the cock, and I gain my purpoſe. In
this method, however, unleſs the pump be very
good, and ſeveral contrivances, too minute to be
particularly deſcribed, be made uſe of, a good
deal of common air will get into the receiver.
In order to take the electric ſpark in a quantity
of
any
kind of air, which muſt be very ſmall, to
produce a ſenſible effect upon it, in a ſhort time,
by means of a common machine, I put a piece of
wire into the end of a ſmall tube, and faſten it with
hot cement, as in Pl. II. fig. 16; and having got the
air I want into the tube, I place it inverted in a baron
containing either quickſilver, or any other fluid
ſubſtance by which I chuſe to have the air con-
fined. I then, by the help of the air-pump, drive
out as much of the air as I think convenient, ad-
mitting the quickſilver, &c. to it, as at a, and
putting a braſs ball on the end of the wire, I take
the ſparks or ſhocks upon it, and thereby trans-
mit them through the air to the liquor in the
tube.
To take the electric ſparks in any kind of Auid,
as oil, &c. I uſe the ſame apparatus deſcribed
above, and having poured into the tube as much
of the fluid as I conjecture I can make the electric
ſpark paſs thicugh, I fill the reſt with quickſilver;
and placing it inverted in a baſon of quickſilver,
I take the ſparks as before.
1
D 2
If
36
Sez. III.
THE
INTRODUCTION.
If air be generated very faſt by this proceſs,
I uſe a tube that is narrow at the top, and
grows wider below, as fig. 17, that the quickſilver
may not recede too ſoon beyond the ſtriking diſ-
tance.
Sometimes I have uſed a different apparatus for
this purpoſe, repreſented fig. 18. Taking a pretty
wide glafs tube, hermetically ſealed at the upper
end, and open below; at about an inch, or at
what diſtance I think convenient from the top, I
get two holes made in it, oppoſite to each other.
Through theſe I put two wires, and faſtening them
with warm cement, I fix them at what diſtance I
pleaſe froin each other. Between theſe wires I
take the ſparks, and the bubbles of air riſe, as
they are formed, to the top of the tube.
I have found it very convenient to have a number
of glaſs veſſels, ſuch as repreſented Pl. V. fig. 2, for
the purpoſe of making a quantity of air paſs through
a body of water, or any kind of Auid, or any ſub-
ſtance in the form of powder ; the air entering by
the tube which goes to the bottom of the veſſel,
and being delivered by that which is inſerted only at
the top. I alſo found it neceſſary to have theſe vef-
fels of various ſizes, the largeſt containing about a
pint, and the ſmalleſt about half an ounce meaſure of
The larger end of this veffel I have generally
cloſed with a cork, and cement; but I ſometimes
found it neceſſary to have this part alſo of glaſs,
with
4
water.
Sect. II.
THE INTRODUCTION.
37
with only two ſmall perforations, for the inſertion of
glaſs tubes.
I have frequently had occaſion to make uſe of a
great
number of theſe veſſels at the ſame time, ſo
diſpoſed, as that the fame air might paſs through
them all in ſucceſſion, in the manner repreſented,
fig. 3.
In ſome caſes, however, I found it neceſſary to
exclude all cement, and every kind of luting, from
an apparatus of this kind; having had all the glaſs
tubes fitted to their ſeveral holes by grinding. But
this makes the apparatus very expenſive, and eſpeci-
ally the repairs of it.
Annexed to the laſt-mentioned apparatus, is a
long phial, a fig. 3, with a tube fitted to it by grind-
ing, and bent, ſo as to diſcharge the air, or vapour,
ifiuing from it, downwards. This kind of phial I
have generally uſed for my experiments with nitrous
vapour. The phial is deep, in order to admit a
ſudden and violent efferveſcence without the danger
of the liquor being thrown over, and the tube ſhould
be long enough, to go to the bottom of any veſel
in which the vapour is to be delivered.
In diſtilling ſpirit of nitre, I have generally made uſe
of the apparatus repreſented Pl. V. fig. 4, which was
invented by Mr. Woulfe, conſiſting of a retort a, an
adopter, if neceſſary, b, and a receiver c, with two
orifices; one d, for the diſcharge of the diſtilled acid,
and
D 3
38
SeEt. III.
THE INTRODUCTION.
1
and the other e, to ſerve as an outlet for the ſuper-
abundant vapour ; which, paſſing through the glaſs
tube f, may impregnate the water in the baſun g.
Pl. III. fig. 4, repreſents a cylindrical veſſel made of
tin, incloſing another of iron wire. In the outer veſſel
a charcoal fire may be made, ſurrounding the inner
cylinder, which, being open at the bottom, will
admit the upper part of a glaſs jar, ſupported in
whatever manner the operator may find moſt con-
venient. Thus a jar, with the air, &c. contained
in it, may be heated as much as the glaſs will bear,
without giving more heat than is neceſſary to the
lower
part
of it. In this manner alſo, an equal de-
gree of heat may be given to every ſide of the upper
part of the glaſs.
Pl. III. fig. 5, explains the manner in which I make
an electrical exploſion paſs through any ſubſtance in
the form of vapour. It repreſents a glaſs fyphon,
in each leg of which is an iron wire, of ſuch a length,
that there ſhall only be about half an inch between
the heads of them. The ſyphon muſt be filled
with mercury, and each of the legs inſerted in fepa-
rate baſons, alſo containing mercury. After this,
the ſubſtance may be introduced into the ſyphon by
means of a glaſs tube, and, being lighter, it will
take its place in the bend of the ſyphon ; which
may then be placed near the opening of a ſmall fur-
nace, or in the apparatus deſcribed fig. 3, when what-
ever
Sez. III.
39
THE INTRODUCTION.
ever lodges in the upper part of the ſyphon will be
converted into vapour, and the exploſion will be
made in it by making the fyphon part of an electri-
cal circuit. Mercury itſelf may be converted into
vapour in the ſame manner.
It may be worth while to give a ſhort account of
the earthen jar, in which I made many of the ex-
periments on the growth of plants in different kinds
of air, recited in this volume; and a bare inſpection
of Pl. VI. fig. I, will be almoſt fufficient for this
purpoſe.
The jar was about eighteen inches in diameter at
the top, and of the ſame depth. It was placed in
an open expoſure in the garden, and ſticks were
thiuft into the earth in a perpendicular poſition,
quite round it; and to theſe ſticks glaſs jars, filled
with water, with their mouths inverted in the water
of the earthen jar, were faſtened by ſtrings. After
I had introduced into one of theſe jars any particular
kind of air, I afterwards drew through the water,
and put into it, any plant, the top and leaves of
which I wiſhed to expoſe to it ; ſupporting the root
or ſtalk at a proper height in the carthen jar, if I
found that any ſuch ſupport was neceſſary. In ſome
caſes, it will be found that the top of the plant was in
one jar, and the root or ſtalk in another ; which it
was not at all difficult to do.
Fig.
1
j
D 4
40
Sext. III.
THE INTRODUCTION,
Pl. VI. fig. 2, repreſents the inſtrument by which !
endeåvoured to aſcertain the conducting power of dif-
ferent kinds of air with reſpect to heat. It conſiſts
of a glaſs bulb open at both ends, ſo that I could ca-
fily faſten a thermometer with its bulb in the center
of it, where it would be ſurrounded by any kind of
air, introduced into it after it had been previouſly
filled with mercury. The manner in which the ex-
periments were made is ſufficiently deſcribed in the
account of them.
Pl. VII. fig. 1, is a view of the apparatus with
which the principal experiments relating to the ſeem-
ing converſion of water into air were made. It
conſiſts of an earthen veſſel, the bulb of which, con-
taining moiſtened clay, is fixed in the inſide of a
glaſs veſel, through which the heat of a burning lens
may be thrown upon it ; while the inſide has a com,
munication with a baſon of water, or mercury,
in
which veſſels may be placed to receive the air that
is forced through the body of the earthen veſſel;
while the water, or mercury, in the bafon in which
the glaſs veſſel ſtands, riſes within it, to ſupply the
place of that air.
Pl.VII.fig. 2, ſhews the diſpoſition of the apparatus
by which ſteam is tranſmitted through a red-hot tube,
containing iron, &c. with a worin tub to collect the
fuperfluous water, &c. and a veſſel to receive the
air
SEEF. II.
4.1
THE INTRODUCTION.
air that is produced. This veſſel is here drawn
very ſmall, that it might not take up much room
in the plate; but I have generally uſed a large
trough for this purpoſe, and jars of conſiderable
ſize to receive the air. Inſtead of the finall furnace
to heat the water, &c. I now uſe one of Mr. Ar-
gend's lamps, which is, on ſeveral accounts, a very
valuable addition to a chemical apparatus. Fig. 6,
repreſents the method of receiving the air in this
proceſs under a funnel, fixed in a trough of water,
which may be uſed when large balloons are filed,
and when no account is taken of any water that is
condenſed in the proceſs.
Fig. 4, repreſents a large glaſs balloon, in which
inflammable air, iſſuing from the orifice of a finall
tube, burns like a candle, while the water produced
by the proceſs is collected in the inſide of it.
Fig. 5, repreſents a ſtrong cylindrical glaſs vef-
fel, in which infiammable and dephlogiſticated air
may be fired. It is furniſhed with a wooden cap,
firmly cemented to the open end of it, and cloſed
with a ſcrew, and two iron wires are inſerted at the
top of it, between which an electric ſpark can be
taken.
1
ADVER-
i
ADVERTISEMENT.
TH
HE weights mentioned in the courſe of this trea-
tiſe are Troy, cnd what is called an ounce
meaſure of air, is the ſpace occupied by an ouncc weight
of water, which is equal to 480 grains, and is,
therefore, almoſt two cubic inches of water ; for one
cubic inch weighs 254 grains. Having foinetimes uſed
the penny-weight, it may be neceſſary to acquaint Fo-
reigners, that 24 grains are a penny-weight, that 20
of ſuch penny-weights make an ounce, and 12 ounces a
pound.
The ſame ounce Troy, is, by Apothecaries, divided
into eight drams, each dram into three fcruplesy and
the ſcruple into twenty grains.
1
+
Β Ο Ο Κ Ι.
OBSERVATIONS AND EXPERIMENTS RE.
LATING TO FIXED AIR.
PART
1.
OF THE RELATION OF FIXED AIR TO WATER.
SECTION 1.
Of the impregnation of water with fixed air.
I
T was in conſequence of living for ſome time in
the neighbourhood of a public brewery, a little
after Midſummer in 1767, that I was induced to
make experiments on fixed air, of which there is
always a large body, ready formed, on the ſurface
of the fermenting liquor, generally about nine inches,
or a foot, in depth, within which any kind of ſub-
ſtance may be very conveniently placed ; and though,
in theſe circumſtances, the fixed air muſt be conti-
nually mixing with the common air, and is there-
fore
44
Part I
OBSERVATIONS ON FIXED AIR.
fore far from being perfectly pure, yet there is a
conſtant freſh fupply from the fermenting liquor,
and it is pure enough for many purpoſes.
A perſon, who is quite a ſtranger to the properties of
this kind of air, would be agreeably amuſed with extin-
guiſhing lighted candles, or chips of wood in it, as
it lies upon the ſurface of the fermenting liquor. For
the ſmoke readily unites with this kind of air, pro-
bably by means of the water which it contains ; fo
that very little or none of the ſmoke will eſcape into
the open air, which is incumbent upon it. It is re-
markable, that the upper ſurface of this finoke,
floating in the fixed air, is ſmooth, and well defined;
whereas the lower ſurface is exceedingly ragged, fe-
veral parts hanging down to a conſiderable diſtance
within the body of the fixed air, and fometimes in
the form of balls, connected to the upper ſtratum
by Nender threads, as if they were ſuſpended. The
ſmoke is alſo apt to form itſelf into broad Aakes,
parallel to the ſurface of the liquor, and at different
diſtances from it, exactly like clouds. Theſe ap-
pearances will fometimes continue above an hour,
with very little variation. When this fixed air is
very ſtrong, the ſmoke of a ſmall quantity of gun-
powder fired in it will be wholly retained by it, no
part eſcaping into the common air.
Making an agitation in this air, the ſurface of it
(which ſtill continues to be exactly defined) is thrown
into
H
Seet. I.
45
OBSERVATIONS ON FIXED AIR.
into the form of waves, which is very amuſing to
look upon ; and if, by this agitation, any of the
fixed air be thrown over the ſide of the veſſel, the
ſmoke, which is mixed with it, will fall to the
ground, as if it was ſo much water, the fixed air
being heavier than common air.
Fixed air does not inſtantly mix with common air.
Indeed if it did, it could not be caught upon
the
ſurface of the fermenting liquor. A candle put under
a large receiver, and immediately plunged very deep
below the ſurface of the fixed air, will burn foine time.
But veſſels with the ſmalleſtorifices, hanging with their
mouths downwards in the fixed air, will in time have
the common air, which they contain, perfectly mix-
ed with it. When the fermenting liquor is con-
tained in veſſels cloſe covered up, the fixed air, on
removing the cover, readily affects the common air
which is contiguous to it; ſo that, candles held at
a confiderable diſtance above the ſurface will inſtantly
I have been told by the workmen, that
this will ſometines be the caſe, when the candles
are held two feet above the mouth of the veſſel.
Fixed air unites with the ſmoke of roſin, ſulphur,
and other electrical ſubſtances, as well as with the
vapour of water.
I alſo held fome oil of vitriol in a glaſs veſſel
within the fixed air, and by plunging a piece of red-
hot glaſs into it, raiſed a copious and thick fume.
?
go out.
2
This
46
Part I
OBSERVATIONS ON FIXED AIR.
1
This floated upon the ſurface of the fixed air like
other fumes, and continued as long.
Conſidering the near affinity between water and
fixed air, I concluded that if a quantity of water
was placed near the yeaſt of the fermenting liquor,
it could not fail to imbibe that air, and thereby ac-
quire the principal properties of Pyrmont, and ſome
other medicinal mineral waters. Accordingly, I
found, that when the ſurface of the water was con-
ſiderable, it always acquired the pleaſant acidulous
taſte that Pyrmont water has. The readieſt way
of
impregnating water with this virtue, in theſe cir-
cumſtances, is to take two veſſels, and to keep
pouring the water from one into the other, when
they are both of them held as near the yeaſt as pof-
ſible ; for by this means a great quantity of ſurface
is expoſed to the air, and the ſurface is alſo conti-
nually changing. In this manner, I have ſome-
times, in the ſpace of two or three minutes, made a
glaſs of exceedingly pleaſant ſparkling water, which
could hardly be diſtinguiſhed from very good Pyr-
mont, or rather Seltzer water.
One would naturally think, that having actually
impregnated common water with fixed air, pro-
duced in a brewery, I ſhould immediately have ſet
about doing the ſame thing with air let looſe from
chalk, &c. by ſome of the ſtronger acids. But,
eaſy as the practice proved to be, no method of
doing
1
Seet. I.
47
OBSERVATIONS ON FIXED AIR.
I ſtill con-
doing it at that time occurred to me.
tinued to make my Pyrmont water in the manner
above mentioned till I left that ſituation, which was
about the end of the ſummer 1768; and from that
time, being engaged in other ſimilar purſuits, I
made no more of the Pyrmont water till the ſpring
of the year 1772.
In the mean time I had acquainted all my friends
with what I had done, and frequently expreſſed my
wiſhes that perſons who had the care of large diſtil-
leries (where I was told that fermentation was much
ſtronger than in common breweries) would contrive
to have veſſels of water ſuſpended within the fixed air
which they produced, with a farther contrivance for
agitating the ſurface of the water; as I did not
doubt but that, by this means, they might, wich
little or no expence, make great quantities of Pyr-
mont water; by which they might at the ſame time
both ſerve the public, and benefit themſelves. For
I never had the moſt diſtant thought of making any
advantage of the ſcheme myſelf.
In all this time, viz. froin 1767 to 1772, I ne-
ver heard of any method of impregnating water
with fixed air but that above mentioned. My think-
ing at all of reducing to practice any method of
effecting this, by air diſlodged from chalk, and other
calcareous ſubſtances, was occaſioned by my hear-
ing of Dr. Irving's method of lilţilling fca water
for
F
48
Part 1
OBSERVATIONS ON FIXED AIR.
1
for the uſe of the navy. For it occurred to me, thať
if feamen could be taught a method of impregnating
that or any other water with fixed air, it might be
farther uſeful to prevent, or to cure the ſea ſcurvy,
going upon Dr. Macbride's. idea of fixed air being
an antiſeptic.
Mentioning this ſcheme to Sir George Saville,
he introduced me to Lord Sandwich, then at the
head of the admiralty, who procured an order for
the college of phyſicians to examine it. As they
were pleaſed to recommend the trial of it, I drew
up an account of the method which I had then de-
vifed, in a ſmall pamphlet ; the ſubſtance of which,
as it is no longer publiſhed ſeparately, I inſert here.
1
Directions for impregnating water with fixed air.
If water be only in contact with fixed air, it will
begin to imbibe it, but the mixture is greatly acce-
lerated by agitation, which is continually bringing
freſh particles of air and water into contact. All
that is neceſſary, therefore, to make this proceſs ex-
peditious and effectual, is firſt to procure a ſufficient
quantity of this fixed air, and then to contrive a
method by which the air and water may be ſtrongly
agitated in the ſame veſſel, without any danger of ad-
mitting the common air to them; and this is eaſily done
by firſt filling any veſſel with water, and introducing
the
+
Sect. 1.
49
OBSERVATIONS ON FIXED AIR.
the fixed air to it, while it ſtands inverted in another
veffel of water.
Take therefore a glaſs veſſel, a, Pl. VIII. fig. 1.
with a pretty narrow neck, but ſo formed, that it
will ſtand upright with its mouth downwards (or it
may be ſupported as in Pl. III. fig. 3) and having
filled it with water, lay a ſlip of clean paper, or thin
paſteboard upon it. Then, if they be preſſed cloſe
together, the veſſel may be turned upſide down,
without danger of admitting common air into it;
and when it is thus inverted, it muſt be placed in
another veffel, in the form of a bowl or baſon, b,
with a little water in it, ſo much as to permit the
Пір of
paper or paſteboard to be withdrawn, and the
end of the pipe c to be introduced.
This pipe muſt be flexible, and air-tight, for which
purpoſe it is, I believe, beſt made of leather, fewed
with a waxed thread, in the manner uſed by ſhoe-
makers. Into each end of this pipe a piece of a
quill, or tube of tinned iron, ſhould be thruſt, to
keep them open, while one of them is introduced
into the veſſel of water, and the other into a cork,
which muſt be perforated, and fitted to a veſſel e,
two thirds of which ſhould be filled with chaik, or
pounded marble, well covered with water.
Things being thus prepared, and the veſſel con-
taining the chalk and water being detached from
the veſſel of water, pour a little oil of vitriol upon
the chalk and water, and put the cork into the
VOL, I,
E
bottle
A
!
50
Part 1.
OBSERVATIONS ON FIXED AIR,
1
bottle a little time after the efferveſcence has be.
gun; and then introduce the end of the pipe into
the mouth of the veſſel of water, as in the drawing,
and, if neceſſary, agitate the chalk and water briſka
ly. This will preſently produce a conſiderable
quantity of fixed air, which will force its way
through the pipe, and aſcend into the veſſel of
water, the water at the ſame time deſcending, and
coming into the baſon.
When about one half of the water is forced out,
let the operator lay his hand upon the uppermoſt
part of the veſſel, and ſhake it as briſkly as he can,
and in a few minutes the water will abſorb the
air ; and taking its place, will nearly fill the veſſel
as at the firſt. Then ſhake the phial containing
the chalk and water again, and force more air in-
to the veſſel, till, upon the whole, about an equal
bulk of air has been thrown into it. Alſo ſhake
the water as before, till no more of the air can be
imbibed. As ſoon as this is perceived to be the
caſe, the water is ready for uſe; and if it be not
uſed immediately, ſhould be put into a bottle as ſoon
as poſſible, well corked, and cemented. It will
keep, however, very welly
, if the bottle be only well
corked, and kept with the mouth downwards.
In general, the whole proceſs does not take up
more than about a quarter of an hour, the agitation
not five minutes; and in nearly the ſame time
might a veſſel of water, containing two or three
gallons,
!
Seel, T.
SI
OBSERVATIONS ON FIXED AIR.
+
gallons, or indeed any quantity that a perſon could
well ſhake, be impregnated with fixed air, if the
phial containing the chalk and oil of vitriol, be
larger in the ſame proportion.
To give the water as much air as it can receive
in this way, the proceſs may be repeated with the
water thus impregnated. I generally chuſe to do
it two or three times, but very little will be gained
by repeating it oftener; ſince, after ſome time, as
much fixed air will eſcape from that part of the
ſurface of the water which is expoſed to the com-
mon air, as can be imbibed from within the veſſel.
The preſſure of the atmoſphere aſſiſts very con-
ſiderably in keeping fixed air confined in water ;
for in an exhauſted receiver, Pyrmont water will
abſolutely boil, by the copious diſcharge of its air.
This is alſo the reaſon why beer and ale froth ſo
much in vacuo. I do not doubt, therefore, but
that, by the help of a condenſing engine, water
might be much more highly impregnated with the
virtues of the Pyrmont ſpring; and it would not
be difficult to contrive a method of doing it.
All calcareous ſubſtances contain fixed air, and
any acids may be uſed in order to ſet it looſe from
them; but pounded lime ſtone, or the fawings of
marble, and oil of vitriol are, both of them the
cheapeſt, and, upon the whole, the beſt for the
purpoſe.
E 2
I ſhould
52
OBSERVATIONS ON FIXED AIR.
Part I
1
I
I ſhould think that there can be no doubt, but
that water thus impregnated with fixed air muſt
have all the medicinal virtues of genuine Pyrmont
or Seltzer water; ſince theſe depend upon the
fixed air they contain. If the genuine Pyrmont
water derives any advantage from its being a na-
tural chalybeate, this may alſo be obtained by pro-
viding a common chalybeate water, and uſing it.
in theſe proceſſes, inſtead of common air.
If any perſon would chuſe to make this medi-
cated water more nearly to reſemble genuine Pyr-
mont water, Sir John Pringle informs me, that
from eight to ten drops of Tinktura Martis cumz
Spiritu falis muſt be mixed with every pint of it.
It is agreed, however, on all hands, that the pecu-
liar virtues of Pyrmont, or any other mineral water
which has the ſame briſk or acidulous taſte, depend
not upon its being a chalybeate, but upon the fixed
air which it contains.
But water impregnated with fixed air does of it-
felf diffolve iron, as the ingenious Mr. Lane has
diſcovered; and iron filings put to this medicated
water make a ſtrong and agreeable chalybeate,
ſimilar to ſome other natural chalybeates, which
hold the iron in ſolution by means of fixed air
only, and not by means of any acid; and theſe
chalybeates, I am informed, are generally the moſt
agreeable to the ſtoinach.
Ву
2
Seet. I.
53
OBSERVATIONS ON FIXED AIR,
:
By this proceſs may fixed air be given to wine,
beer, and almoſt any liquor whatever : and when
beer is become flat or dead, it will be revived by
this means; but the delicate agreeable flavour, or
acidulous taſte communicated by the fixed air, and
which is manifeſt in water, will hardly be perceived
in wine, or other liquors which have much taſte
of their own.
I would not interfere with the province of the
phyſician, but I cannot intirely ſatisfy myſelf with-
out taking this opportunity to ſuggeſt ſuch hints
as have occurred to myſelf, or my friends, with re-
ſpect to the medicinal uſes of water impregnated witlı
fixed air, and alſo of fixed air in other applications.
In general, the diſeaſes in which water imprego
nated with fixed air will moſt probably be ſervice-
able, are thoſe of a putrid nature, of which kind
is the ſea-ſcurvy. It can hardly be doubted, alſo,
but that this water muſt have all the medicinal
virtues of Pyrmont water, and of other mineral
waters fimilar to it, whatever they be; eſpecially
if a few iron filings be put to it, to render it a
chalybeate, like gemine Pyrmont water. It is
poſſible, however, that, in ſome caſes, it may be
deſirable to have the fixed air of Pyrmont water,
without the iron which it contains.
Having this opportunity, I ſhall alſo hint the
application of fixed air in the form of clyſters,
which occurred to me while I was attending to
this
E 3
I
}
54
OBSERVATIONS ON FIXED AIR.
Part I.
this ſubject, as what promiſes to be uſeful to cor-
rect putrefaction in the inteſtinal canal, and other
parts of the ſyſtem to which it may, by this chan-
nel, be conveyed. It has been tried once by Mr.
Hey, of Leeds, and the recovery of the patient
from an alarming putrid fever, when the ftools
were become black, hot, and very fetid, was ſo
circumſtanced, that it is not improbable but that
it might be owing, in ſome meaſure, to thoſe cly-
ſters. The application, however, appeared to be
perfectly eaſy and ſafe. Alſo Dr. Warren, of
Taunton, adminiſtered fixed air in the ſame manner,
with the moſt happy effect.
I cannot help thinking that fixed air might be
applied externally to good advantage in other caſes
of a putrid nature, even when the whole ſyſtem
was affected. There would be no difficulty in
placing the body fo, that the greateſt part of its
ſurface ſhould be expoſed to this kind of air; and
if a piece of putrid fleſh will become firm and
ſweet in that ſituation, as Dr. Macbride found,
ſume advantage, I ſhould think, might be expected
from the fame antiſeptic application, aſſiſted by the
vis vitæ, operating internally, to counteract the
fame putrid tendency. Some Indians, I have been
informed, bury their patients, labouring under pu-
trid diſeaſes, up to the chin in freſh mould, which
is alſo known to take off the fætor from Aeth meat
beginning to putrify. If this practice be of any
uſe,
11
1
Seet. L.
OBSERVATIONS ON FIXED AIR.
55
1
uſe, may it not be owing to the fixed air imbibed
by the pores of the ſkin in that ſituation?
Being no phyſician, I rụn no rifque by throw-
ing out theſe random hints and conjectures. 1
ſhall think myſelf happy, if any of them ſhould be
the means of making thoſe perſons, whom they
immediately concern, attend more particularly to
the ſubject.
There is another ingenious method of impregnating-
water with fixed air, contrived by Dr. Nooth, by
means of three glaſs veſels, as repreſented in Pl. IX:
In the loweſt veffel, the chalk or marble, and
the water acidulated with oil of vitriol, muſt be
put, and into the middle veſſel the water to be
impregnated. During the efferveſcence, the fixed
air riſes into the middle veſiel, and refts upon the
ſurface of the water in it, while the water that is
diſplaced by the air riſes through the bent tube
into the uppern oft veſſel, the common air going
out through the channel in the ſtopper. When
the bent tube is of a proper length, the proceſs
requires no attention; and if the production of air
be copious, the water will generally be fufficiently
impregnated in five or ſix hours. At leaſt, all the
attention that needs be given to it is to raiſe the
uppermoft veſſel once or twice, to let out that part'
of the fixed air which is not readily abſorbed by
If the operator chuſe to accelerate the
proceſs, by agitating the water, he muft ſeparate
the
ܪ
*
water.
E A
1
56
Part 1,
OESERVATIONS ON FIXED AIR.
the two uppermoſt veſſels from the loweſt. For
if he ſhould agitate them all together, he will oc-
caſion too copious a. production of air; and he
will alſo be in danger of throwing the liquor con-
tained in the loweſt vefſel into contact with the
ſtopper which ſeparates it from the middle veſſel,
by which means ſome of the oil of vitriol might
get into the water.
SE C T I O N II.
.
Of the State of Air in Water.
A
FTER treating of the impregnation of water
with fixed air, I ſhall recite the obſervations
I have at different times made on the Itate of air
expelled from water by heat, eſpecially as in ſeve-
ral caſes this is fixed air.
I have frequently found air expelled from water to
be much better than common air ; but I have not yet
undertaken any regular courſe of experiments on the
ſubject; ſuch as examining the fame water at different
times of the year, with different impregnations, differ-
ent expoſures, &c. which I wiſh to have done; be-
cauſe I think it poſſible, that ſomething worth
know-
Sect. II,
57
OBSERVATIONS ON FIXED AIR,
5
knowing relating to the properties of water, or of
air in water, eſpecially reſpecting phlogiſton, and
the general ſtate of the atmoſphere, may be dif-
covered by this means, Such obſervations as I
have occaſionally made I ſhall here put down.
Boiling generally expels more or leſs of fixed
air from water. On the 5th of June, 1779, I
found my pump water to yield air, one fifth of
which was fixed air, and the meaſures of the teſt
for the reſiduum were 1. 5.* The fame pump
water; · which had been boiled ſome time before;
gave air, one feventh of which was fixed air, and
the meaſures of the teſt for the reſiduum were 1. 4.
In general I believe a greater difference than this
will be found in theſe two caſes. I do not know
that water will attract fixed air from the atmoſphere,
at leaſt in the proportion in which it is generally
found in pump water, which is probably acquired
from calcareous matters firſt held in folution, and
then partially decompoſed in it.
Water diſtilled in a glaſs, which had been long
expoſed to the open air, yielded air, of which little
or none was fixed air, and with equal quantities of
nitrous air, the meaſures of the teſt were 1.1.
A quantity of rain water taken from a large tub,
which had long ſtood expoſed to the open air, yield-
In the experiments mentioned in this book, the two kinds of
air were not agitated when they were mixed.
ed
.
1
OBSERVATIONS ON FIXED AIR.
Part 1
ed one ſixtieth of its bulk of air, of which no
part was fixed air, and the meaſures of the teſt
were 1.4. Perhaps the wood of the tub, or ſome
other matter caſually falling into it, might have con-
taminated this air.
A quantity of river water, not very far from the
ſpring, gave one fiftieth of its bulk of air of which
the ſmalleſt part imaginable was fixed air, and the
meaſures of the teſt were 1.05. This air was very
pure; but the part of the river from which I took
it was nearly ſtagnant, and very full of water
plants.
Lime water is certain not to contain any fixed
air. From a quantity of this water I expelled air ſo
pure that the meaſures of the teſt were 1.0. The
quantity of air was one fiftieth of its bulk. Upon
the whole I am inclined to infer, from all the obſer-
vations I have hitherto made, that this is about the
ſtandard of air contained in water, which has no fixed
air, and has been expoſed to no influences except
thoſe of the common atmoſphere, in its uſual
ſtate.
From a ſpring which was remarkable for its pe-
trefying quality, I expected much fixed air, but I
found none; and the air I extracted from it was a
little worſe than common air. It is plain that, in
this caſe, à boiling heat had not decompoſed the
lime ſtone it contained
I alſo
1
1
1
Sect. II.
59
OBSERVATIONS ON FIXED AIR,
1
I alſo filled a phial with pump water and pound-
ed lime ſtone, expoſed to the fun from the 28th of
May to the 3d of July, when it yielded air ſo pure,
that with two equal quantities of nitrous air, the
meaſures of the teſt were 1.04. I ſhould have fuf-
pected ſome green vegetable matter in this water,
but I could not perceive any. . Perhaps ſome latent,
or naſcent vegetation, might be the cauſe of this
very pure air.
That water imbibes dephlogiſticated air from the
atmoſphere, is evident from the following obſer-
vation. I took ſome of the Briſtol water in which
fiſhes had died, and which then yielded air tho-
roughly phlogiſticated ; and having expoſed it to
the ſun from the 28th of May to the 3d of July, I
found it to yield a conſiderable quantity of air ; and
ſo pure that, with an equal quantity of nitrous air,
the meaſures of the teſt were 0.76, and with two
cqual quantities of nitrous air the meaſures were
I.18.
Fixed air abounds ſo much in fome mineral wa-
ters, that their peculiar virtues are certainly owing
to this ingredient in their compoſition. This con-
fideration has led ſome perſons to aſcribe the virtues
of other inineral waters to this principle, though
they contain it in fo very ſinall a proportion, as to
make that opinion very improbable. Some, for in-
Nance, have thought that the virtues of the Bath-
water
1
60
Part I.
OBSERVATIONS ON FIXED AIR.
watex were owing, in a great meaſure, to the fixed
air it contains ; and living at no great diſtance from
that celebrated ſpring, I thought I ſhould incur a
juſt cenſure, if I did not endeavour to aſcertain what
kind of air is contained in that water, and in what
proportion. Accordingly, I made an excurſion as
far as Bath, chiefly with that view, and made the
following experiments, which, having no apparatus
of my own along with me, I was enabled to perform
by the friendly zeal and ingenuity of Mr. Painter;
Dr. Guſthart, Dr. Falconer, and Dr, Watſon, fa-
vouring me with their preſence,
In order to aſcertain what proportion of air is con-
tained in the water, in the ſtate in which it is drank, I
filled a pint-phial with the water hot from the pump,
and expelled the air from it, by boiling it about four
hours, receiving the produce in quickſilver. This
air was about one thirtieth of the bulk of the water,
and about one half of it was fixed air, precipitating
lime in lime-water, and being readily abſorbed by wa-
ter. The reſiduum appeared, by the teſt of nitrous air,
to be rather better than air in which a candle had
burned out.
The quantity of fixed air that appears, by this
experiment; to be contained in the Bath-waters is ſo
very ſmall, that I think it very improbable that
their virtues ſhould be at all owing to it. Few
{pring-waters, I believe, contain much leſs fixed air,
and
Sect. II.
66
OBSERVATIONS ON FIXED AIR.
*
and many I know, which have no medicinal virtue
at all, contain more. The pump-water belonging to
the houſe in which I lived at Calne, contains about one
fourteenth of its bulk of fixed air ; and my pump-
water at Leeds, contained about one fiftieth of its
bulk of air, of the very fame compoſition as the air
of the Bath-waters, viz. half of it fixed air, and
half common air, a little phlogiſticated, ſo as to be
in about the ſame ſtate as air in which a candle had
burned out.
Beſides, the length of time which the Bath-wa-
ters, and indeed moſt other ſpring-waters, require
to expel the air by means of heat, ſhews that the air
expelled from them, was not contained in them
in that ſtate in which it is contained in waters pro-
perly impregnated with fixed air, out of which
it may always be expelled by the heat of boil-
ing water in leſs than an hour. In fact, the
fixed air is not united to the water, but to ſome cal-
carequis inatter in the water, out of which the air is
expelled with much more difficulty. Accordingly,
Dr. Falconer. informs me, that there is a depoſit
made by this water, after long boiling. If ſo, it inay
be preſumed, that theſe waters do not ſo properly
contain fixed air, as a calcareous earth; which,
though it contain fixed air, may not part with it in
the ſtomach, unleſs it meet with ſome acid to dę-
compoſe it.
Besides
-
62 OBSERVATIONS ON FIXED AIR.
Part I.
Beſides the air contained in the Bath-water, there
is a conſiderable quantity of air continually bubbling
up from almoſt every part of the ſoil, through the
water in the bath. To examine this, I took about a
pint of that air, and found, upon examination, that only
about one twentieth of its bulk was fixed air, preci-
pitating lime in lime-water, and being readily ab-
forbed by water. The reſt extinguiſhed a candle,
and was ſo far phlogiſticated, that two meaſures of
it, and one of nitrous air, occupied the ſpace of
21% of a meaſure ; that is, it was almoſt perfectly
noxious.
Being in Germany in the ſummer of the year
1774, wę happened to paſs by the famous ſpring
of Seltzer-water, near Schwallbach, and alſo an-
other very hot ſpring near the road from that place
to Mentz. Through both theſe ſprings there was
a bubbling of air, exactly ſimilar to that in the
Bath-waters; but I had not time, or convenience,
for making the ſame experiments upon them, and
therefore contented myſelf with finding that the air
of both of them extinguiſhed a candle.
PART
1
*
1
PART
II.
OF THE SUBSTANCES WHICH YIELD FIXED AIR
CHIEFLY BY HEAT.
SECTION 1.
Of Air extracted from mineral Subſtances.
HAVIN
AVING in an early period of my experiments,
found that manganeſe, and other natural mi-
neral ſubſtances, yield a very pure air by extreme
heat; it occurred to me that ſubterraneous fires
might maintain themſelves by means of the air
which they diſodged from ſuch ſubſtances as they
found in the bowels of the earth. This led me to
try what kind, and what quantity of air, would be
yielded by various mineral ſubſtances, in great heats,
and it may not be uſeleſs to recite the expériments, as
a knowledge of the reſults may be uſeful in other
philoſophical inquiries ; and as many of them yielderi
fixed air, I ſhall inſert the account of them in this
place.
As the original object of my inquiry refpected
sclcanic fires, I gave particular attention to the exa-
mination
1
1
64
Part I.
OBSERVATIONS ON FIXED AIR.
1
mination of volcanic fubſtances, eſpecially with a
view to aſcertain whether a ſubſtance which had
been in a ſtate of fuſion will yield air by being heated
again or not; in order to diſtinguiſh the products
of volcanos from other ſtony matters. Though
charcoal, which has been expoſed to the moſt in-
tenſe heat, will imbibe air from the atmoſphere, and
give it out on being heated a ſecond time, yet this is
not a ſubſtance that can be fuſed; and as this does
not appear to be the property of earthy ſubſtances,
fome dependence may perhaps be placed on this
reſt. If ſo, baſaltes can hardly be claſſed among vol-
canic productions, becauſe they yield more air by
heat than any known lava that I have met with.
But Mr. Keir has obſerved to me, that a ſub-
ſtance froin which air has been expelled by fuſion,
may yield more air by being melted again in a great-
er degree of heat, ſo that this teſt is not deciſive.
As the reſults of the experiments that I made both
with lavas and baſaltes were various, I ſhall briefly
cite them.
Of lava from Iceland, four ounces and one fifth,
heated in an earthen retort, gave twenty ounce
meaſures of air, of which one half, towards the be-
ginning of the proceſs, was fixed air, and the re-
mainder of the ſtandard of 1.72, extinguiſhing a
candle. In the interſtices of this lava, there was a
browniſh fand, which I could not ſeparate from it.
Of.
1
1
Seft. 1.
65
OBSERVATIONS ON FISED AIR.
i
Of lava from Veſuvius, five ounces and a half,
yielded thirty ounce meaſures of air, of which the
firſt portion had a ſight appearance of fixed air,
and the reſt was phlogiſticated, from the ſtandard
of 1.64, to 1.38, which came laft. The retort
was broken by the ſwelling of the maſs in cooling.
Another ounce of lava, of the conſiſtence of a hard
ſtone, yielded only three ounce and a half meaſures
of air, chiefly infiammable, which, I ſuppoſe, came
from the gun-barrel in which this particular experi-
ment was inade.
From theſe experiments it ſeems probable, that
genuine lavas do not give much air; but this will
depend upon the degree of heat to which they have
been ſubjected in the ſubterraneous fire.
It has been much diſputed whether baſaltes be a
volcanic production, or only a cryſtalization of a
maſs of matter in a fluid form. The following ex-
periments incline me to the latter opinion.
Seven ounces of bafaltes from Scotland, heated
in an earthen retort, yielded 104 ounce meaſures of
air, of which the firſt portion had a light appear-
ance of fixed air, and was ſo much phlogiſticated
as to extinguiſh a candie, being ſometimes of the
Itandard of 1.68.
About two ounces of the giants cauſeway in Ire-
land, yielded forty ounce meatures of air, the firſt
portion of which had a ſlight appearance of fixed air,
VOL. I.
F
an
66
Part IT.
OBSERVATIONS ON FIXED AIR.
and the reſt phlogiſticated, of the ſtandard of 1.65.
It was reduced by fuſion to a hard black glaſs.
Of baſaltes from Scotland, five ounces one hun-
dred and ſixty-two grains, yielded ſeventy-eight
ounce meaſures of air, of which no part appeared to
be fixed air ; but was all phlogiſticated, fome-
times of the ſtandard of 1.7, and towards the laſt
1.41.
The neighbourhood of Birmingham abounds with
a ſtone which, from its being chiefly got from a
village called Rowley, near Dudley, is commonly
called Rowley-rag. When it is broken, it very
much reſembles baſaltes, though it is not found in
the ſame regular form. Dr. WITHERING, of this
place, has given a moſt excellent analyſis of this
ſubſtance, which may be ſeen in a late volume of
the Philoſophical Tranſactions. All that I did with
reſpect to it was, to ſubject it to a ſtrong heat in an
earthen retort ; and from this mode of examination
it ſhould ſeem to be of the fame nature with the ba-
faltes, whatever that be.
Four ounces of the Rowley-rag yielded forty
ounce meaſures of air, containing hardly any ap-
pearance of fixed air, but was phlogiſticated, of
the ſtandard of 1.6, and 1.5; the laſt portion 1.31.
It was reduced to a black glaſſy ſubſtance, which
broke with a poliſh, exactly reſembling that which
remained from the baſaltes.
The
V
Seet. T.
67
OBSERVATIONS ON FIXED AIR.
The Derbyſhire toadſtone, in its appearance, very
much reſembles the Rowley-rag, excepting that it
is full of white ſpots, conſiſting of a calcareous ſub-
ſtance. Dr. WITHERING has analyſed this, as well
as the Rowley-rag, and both from his experiments and
mine, they ſeem to be nearly a-kin to each other.
Two ounces and 384 grains of this ſubſtance,
from which the calcareous part had been diſſolved
by ſpirit of nitre, yielded ſixty ounce meaſures of
air, the firſt portion of which contained a little
fixed air, perhaps from ſome unperceived remains
of the calcareous matter. The reſt was phlogiſti-
cated, of the ſtandard of 1.7.
In another experiment, an ounce and a quarter
of this ſubſtance, from which the calcareous part
had been extracted firſt by oil of vitriol, and then
by ſpirit of nitre, yielded 40 ounce meaſures of
air, of the fame quality of that in the former
proceſs. There remained from both of them a
black glaſly matter, which ſeemed to be very
liquid when it was hot, as part of it had boiled
up into the neck of the retort.
Granite, like baſaltes, has been thought by ſome
to be the product of volcanoes, and by others to
be a cryſtalization from a liquid ſtate. The latter
is the opinion favoured (but for the reaſon given
above not deciſively proved) by theſe experiments.
From about an ounce and an half of this ſub-
ftance
1
F 2
1
68
Part II
OBSERVATIONS ON FIXED AIR.
ſtance I got twenty ounce meaſures of air, the firſt
portion of which contained a little fixed air, but
the reſt was phlogiſticated, from 1.7 to 1.28,
which is nearly the ſtandard of common air; but
the heat was very intenſe, as the ſubſtance was
reduced to a glaſs.
Again, five ounces and 252 grains of a blue
granite yielded feventy ounce meaſures of air, of
the fame quality with the preceding. It was alſo
reduced to a firin uniform glaſly ſubſtance, of a
dark-brown colour. Upon the whole, therefore,
it ſeems probable, that the origin of granite is
ſimilar to that of baſaltes.
In Cornwall there is a ſubſtance called elvain,
the natural hiſtory of which is very like that of
granite, and the reſult of my experiments upon
it ſhews that they are of the ſame nature. There
is a black and white kind of elvain.
Of the black elvain one ounce and 288 grains
yielded twenty-five ounce meaſures of air, the firſt
portion of which contained a little fixed air, and
the reſt was phlogiſticated, of the ſtandard of 1.54.
It was melted into a browniſh black maſs.
Of the white elvain one ounce and 384 grains
yielded thirty ounce meaſures of air, of the ſame
quality with the preceding.
It was converted
into a very porous ſubſtance, exactly reſembling a
pumice ſtone, but much harder.
The
+
Set, I.
69
OBSERVATIONS ON FIXED AIR.
The ſubſtance called groan clay is ſaid to be
formed by the decompoſition of granite. Of this
ſubſtance one ounce and ſeventy-two grains yielded
thirty-two ounce meaſures of air, containing no
ſenſible quantity of fixed air, but all phlogiſticated,
of the ſtandard of 1.62 and 1.33. After the ex-
periment this matter was eaſily ſhaken out of the
retort, and was not ſenſibly changed in its ap-
pearance:
Such were the experiments that I made with
ſubſtances that are, or are ſuppoſed to be, volcanic.
Of thoſe which are certainly 110t volcanic, but
which may come in the way of volcanic fires, I
found thoſe into which the vitriolic acid enters to
yield the greateſt quantity of pure airs; but by no
means ſufficient to keep alive ſuch fires as we
make on the ſurface of the earth.
From ſeven ounces of gypſum, which I kept in
a ſtrong heat twelve hours, I got 230 ounce mea-
ſures of air, the greateſt part of which would have
extinguiſhed a candle; the moſt phlogiſticated be-
ing of the ſtandard of 1.8, but it was afterwards
much purer; and at the laſt conſiderably dephlo-
giſticated; for with two equal meaſures of nitrous
air, the teſt was 1.3. The air was very turbid as
it was produced, and the pureſt of all came ra-
pidly, at the end of the proceſs. It is poſſible
that,
F 3
70
Part II.
OBSERVATIONS ON FIXED AIR.
that, with a ſtronger heat, more, and purer air
might have been procured.
The ſubſtance was
reduced to a hard maſs, yellow next to the retort,
but in the middle very white.
The Stones which I found to furniſh the greateſt
quantity of air, though not the pureſt, were thoſe
of the ſchiſtus kind, which are found in great
quantities in many mountainous countries; and
after being ſubjected to a very great heat, have
the neareſt reſemblance to the generality of lavas
of any ſubſtance on which I have yet made thé
experiment.
From four ounces of a blue Nate I got 320
ounce meaſures of air, a very ſmall portion of
which was fixed air, and the greateſt part of the
reſt (the whole, I believe, except about twenty
ounce meaſures) ſo impure, that the ſtandard was
generally 1.8. Towards the laſt it was 1.5, and
the laſt of all 1.35; ſo that a candle would juſt
have burned in it. The air was very turbid, and
had a very ſtrong ſmell. The ſubſtance was per-
fectly vitrified, and quite black, exactly reſembling
lava. It then weighed, as nearly as I could gueſs
(for in the fuſion it had adhered cloſely to the re-
tort) three ounces and 288 grains.
From eight ounces of another kind of ſchiſtus,
I got ſeventy ounce meaſures of air, of the ſame
quality
1
!
Seet. I.
7.19
OBSERVATIONS ON FIXED AIR.
quality with that in the preceding experiment;
and it was melted into a black maſs, harder than
the former, ſo as to make a ſtill more perfect lava.
Oil of vitriol has been ſuppoſed to enter into
the compoſition of clay. From four ounces of it
I got twenty ounce meaſures of air, in every por-
tion of which one-tenth was fixed air, and the
reſt of the ſtandard of 1.72, 1.52, and at laſt 1.44.
Putting oil of vitriol to this clay, it yielded
much more air, and of a better quality. Two
ounces of the clay, moiſtened with this acid, gave
210 ounce meaſures of air, exceedingly turbid,
containing very little fixed air, and the reſt of the
ſtandard of 1.5, 1.7, 1.58, in the order in which
they are here put down ; but the laſt portion was
1.08, and was conſiderably dephlogiſticated.
A quantity of fine white clay from the Apolla-
chian mountains gave air of the ſame kind at the
beginning of the proceſs with common clay, but
the retort being cracked, the experiment was in-
terrupted.
Nothing in the form of a ſtone yields ſo much
air as lime ſtone, and this is by no means all fixed
air, as I believe has generally been ſuppoſed. For
a very great proportion of it is more or leſs phlo-
giſticated, and the laſt portions often tolerably pure,
fo that a candle would nearly burn in it.
F4
Froin
ame
72
L
Part IT.
OBSERVATIONS ON FIXED AIR.
A
From four ounces of white cryſtals of lime ſtone
.
I got 8.30 ounce meaſures of air, the firſt portion
of which had only one-fourth of fixed air, but in
the courſe of the experiment it varied, being once
three-fourths, then one-half, and at the laſt one-
third. The ſtandard of the reſiduum was never
better than 1.56, nor worſe than 1.66.
From five ounces and a half of lime ſtone of
an excellent kind, I got in all 1160 ounce mea-
ſures of air. Of this one-tenth only was phlogiſ-
ticated, and the reſt fixed, but the laſt portion of
all was half phlogiſticated.
From ſeven ounces of a tranſparent ſubſtance,
found in a ſtone in the neighbourhood of Oxford,
which is chiefly calcareous, I got 1280 ounce
meaſures of air, of which about one-third of the
the whole was fixed air. The ſtandard of the
reſiduuin was at firſt 1.55, and afterwards 1.44.
From ſix ounces of a blue ſtone, found in the
neighbourhood of Stratford, I got 1030 ounce
meaſures of air, of which, till near the end of the
proceſs, about one half was fixed air, and at the
laſt about one fourth. The ſtandard of the remain-
der was about 1.6.
From three ounces of chalk I got 6.30 ounce
meaſures of air, of which at the firſt one fourth
was fixed air, then almoſt two-thirds, then ſome-
thing
1
Sect. I.
73
OBSERVATIONS ON FIXED AIR.
1
thing more than one half, and again a little more
than a third. The ſtandard of the reſduum was
from 1.66 to 1.34.
The pureſt calcareous earth is chalk, and the
moſt perfect chalk is that which is called whiting,
which is therefore uſeful in many experments, ſo
that it is worth while to know what ar it con-
tains. From ſeven ounces of this ſubſtance, I
got, in an earthen retort, 6:30 ounce meaſures of
air, by which it was reduced to four ounces. Every
portion of the air contained about one-third that
was not fixed air, the ſtandard of which was
1.36, 1.38. Again, from ſix ouncis of whiting,
I got 440 ounce meaſures of air, about half of
which was fixed air, and the remainder of the
ſtandard of 1.4.
The whiting was reduced to
three ounces and 312 grains.
In order to try whether any peculiar kind of
air might be procured from whiting faturated with
acids, I moiſtened ſome, which had been well cal-
cined, with water impregnated with vitriolic acid
air; and then by heat expelled from it ninety
ounce meaſures of air, the former part of which
was more than three-fourths fixed air, and the
reſiduum of the ſtandard of 1.5. The laſt portion
had leſs fixed air in it, and the ſtandard of the
refiduum was 1.44. The ſubſtance was rendered
black
74
Part II
OESERVATIONS ON FIXED AIR.
}
black and hard, but in ſpirit of falt it became
white and ſoft.
When quick line is ſuffered to fall in the open
air, it firſt attracts moiſture, and then that moiſture
gives place to fixed air. From three ounces and
ià quarter of this fallen lime I got 375 ounce
meaſures of air, of which about one-fifth was fixed
air, and the ſtandard of the reſiduum was. 1.4.
: Iron ores may be pretty well diſtinguiſhed by
the quality of the air that they yield by heat, as
cwell as by their weight, and external appearance.
:The refidrun of the air from other itony ſub-
ſtances, after the fixed air is ſeparated from it, I
have always found to be phlogiſticated, but that
from iron ore is inflammable.
Three ounces and one-half of white ſpatboſe iroz
ore yielded 560 ounce meaſures of air, of whicli
at the firt one-third was fixed air, then only ſome-
thing more than one half, and again at the laſt a
third. The ſtandard of the reſiduum was about
1.7, and inflammable:
The ſubſtance was re-
duced to one hard maſs, and the bottom of the
carthen retort was melted along with it.
I tried one iron ore that was of a light colour,
and another of a darker. Six ounces of the lighter
coloured ore yielded 750 ounce meaſures of air,
of which at the firſt two-thirds were fixed air, then
5
only
1
1
Sect. I.
75
OBSERVATIONS ON FIXED AIR.
only a little more than a half, and at the laſt a
fifth. The reſiduum of the middle portions of
this air only was inflammable, that of the reſt
phlogiſticated; the ſtandard of it about 1.7. It
was reduced to a hard black Nag full of cavities.
Four ounces of the dark coloured ore yield-
ed 510 ounce meaſures of air, the quality of which
varied very much, like that in the preceding ex-
periment, and the air was not more ſtrongly in-
flammable.
There is, I believe, fome iron in the ſubſtance
that is called black lead (molybdena) and therefore
I mention the experiment that I made with it in
this place. From half an ounce of it I got twenty-
five ounce meaſures of air, of the ſtandard of 1.6,
and 1.42. I have no note of any part of its being
fixed, or inflammable. It had loſt only eighteen
grains in weight. From eight ounces and a half
of another kind of black lead, I got ſixteen ounce
meaſures of air, one fifteenth, or one twentieth of
which was fixed air, and the reſt inflammable,
burning with a blue flame.
I did not purſuc theſe experiments on ores to
any great extent; but having ſome ſtream tin, I
found that 110 grains of it, gave twenty ounce
meaſures of air, a ſmall portion of which was fixed
air, and the remainder of the ſtandard of 1.44,
and at laſt 1.34.
From
.
.
76
LI
OBSERVATIONS ON FIXED AIR.
Part II.
1
1
From two ounces and one fifth of ſteatites, I
got forty three ounce meaſures of air, which had
the ſlighteſt appearance of containing fixed air.
The remainder was thoroughly phlogiſticated, ex-
cept that, at the laſt, it was of the ſtandard of
1.65. It came out of the retort a yellow maſs,
but, powdery, as it was put into it.
Two ounces of terra ponderoſa, gave twenty-ſix
ounce meaſures of air, without any mixture of
fixed air, the ſtandard of it 1.62, 1.42, and 1.29.
The ſubſtance was concreted into one maſs, but
was caſily broken by ſhaking the retort, and then
it did not appear to be changed in its external
appearance.
Two ounces of black wad from Derbyſhire,
yielded eighty ounce meaſures of air, no part of
which was fixed air, but all better than common
air, the ſtandard of it being 1.05. This circum-
ſtance may help to account for this ſubſtance taking
fire, and burning as it does, when it is mixed with
linſeed oil. For if by any means it is ſo far
heated, as to give out its pure air, this muſt alliſt
the combuſtion; and the chemical attraction between
the phlogiſton in the oil, and the dephlogiſticated
matter in the wad may, without its affuming the
form of air, be the cauſe of the maſs becoming hot.
Seven ounces of fluor gave eight ounces of air,
a ſmall proportion of which was fixed air, and the
reſt
1
$
Sext. I.
77
OBSERVATIONS ON FIXED AIR.
reſt of the ſtandard of 1.45. 'It was melted into
a hard maſs. Six ounces of white fluor yielded
in all ten ounce meaſures of air, of which the
Nighteſt portion imaginable was fixed air, the reſt
of the ſtandard of 1.34, and 1.3. In this experi-
ment the bottom of the retort was quite diffolved.
N. B. There was no appearance of fuor acid in
the water in which this air was received, and the
melted maſs gave fluor acid air with oil of vitriol.
From four ounces of a kind of ſand-ſtone, I got
ſeventy five ,ounce meaſures of air, a ſmall por-
tion of which was fixed air, the ſtandard of the
reft, for the moſt part, 1.75, and at the laſt 1.350
When taken out of the retort, it weighed three
ounces and three fourths. That part of it which
was next to the bottom of the retort was whiter
than the reſt, but very hard, adhering to it; and,
what was pretty remarkable, the remainder had ac-
quired juſt as firm a texture as it had before it was
pounded for the purpoſe of the experiment.
Five ounces of a fine white ſand-ſtone, yielded
about ten ounce meaſures of air, containing a little
fixed air, and the reſt of the ſtandard of 1.6. This
alſo was again reduced to a ſtone quite as compact as
it had been before it was pounded.
Six ounces of another fand-ſtone yielded 102
ounce meaſures of air, of which a very ſmall
por-
tion was fixed air, and the reſt of the ſtandard of
1.57,
78
Part II.
OBSERVATIONS ON FIXED AIR.
1.57, and 1.35. This alſo was reduced to a hard
dark coloured ſtone, having ſeparated itſelf from
the retort about a quarter of an inch, except at the
bottom where it adhered to it.
From one ounce and 175 grains of belemnite, I
got 320 ounce meaſures of air, of which at the
firſt one ſixteenth was fixed air, the reſt of the ſtan-
dard of 1.75, 1.55. All the air came while the
heat was very moderate.
From four ounces of cryſtals of quartz, I got 25
ounce meaſures of air, a very ſmall portion of which
was fixed air, the reſt being of the ſtandard of 1.8,
1
and 1.44
I
1
From ſeven ounces of a granulated quartz, got
about ten ounce meaſures of air, containing a little
fixed air, and the reſt of the ſtandard of 1.42. It
came out of the retort a looſe friable ſubſtance,
weighing ſix ounces 290 grains. The retort was
cracked, or more air would probably have been
procured.
From one ounce and eighty four grains of mica,
1
got twelve ounce meaſures of air, of which no
part was fixed air, but of the ſtandard of 1.4, and
1.35
From 120 grains of talc, I got a quantity of air,
but the retort being cracked at the beginning of the
proceſs, I took no account of the quantity. Part
of it was evidently fixed air, and the reſt of the ſtan-
dard
!
!
Seet. I.
OBSERVATIONS ON FIXED AIR.
79
dard of 1.4, and a candle burned in it. The ſub-
ſtance was reduced to a dark hard cinder, adhering.
to the retort.
From four ounces 355 grains of cryſtalized glaſs,
in the form of a whitiſh ſtone, I got twelve ounce
meaſures of air, which contained no fixed air, and
of the ſtandard of 1.42, 1.36, and 1.31. Perhaps
I uſed a greater degree of heat than the glaſs had
been ſubjected to before. Otherwiſe this experiment
might help to account for lava giving fome quan-
tity of air, though it had been in a ſtate of fuſion,
having afterwards cryſtalized, like this glaſs.
The laſt experiment that I ſhall mention was
made with pit coal. Three ounces of ſuch coal as
we have at Birmingham, gave 700 ounce meaſures
of air, of which I could not be fure that any portion
was fixed air. It was all inflammable, the firſt por-
tion of it burning with a white lambent frame, and
the laſt with a blue one.
To the ſubſtances from which I had endeavoured,
at different times, to extract air by heat, it may be
juſt worth while to mention crude antimony. From
one ounce of it, in a glaſs veſſel, and with a redt
ſand heat, I got very little air, not more than its
bulk. The laſt portion was in a great meaſure
fixed air, and the reſiduum extinguiſhed a candle
The antimony on which this experiment was made,
and which had been pounded, formed a concrete:
maſs
so
Part II.
OBSERVATIONS ON FIXED AIR.
maſs when taken from the fire, being mixed with
any of the acids.
A degree of heat fufficient to bake clay, evi-
dently expels fixed air from it. In order to aſcer-
tain this fact, I filled a gun-barrel with tobacco-
pipe clay, and, putting it into the fire, I received
the air that came from it, in ſeveral portions ; but
the whole was not more than about five times the
bulk of the clay. The firſt produce was inflamma-
ble ; but afterwards the air was fixed, preci-
pitating lime in lime-water, and being readily ab-
forbed by water. I never met with purer fixed air.
No calx of any metal on which I made the ex-
periment yielded inflammable air, but all of them
fixed air, and generally in great plenty. Ruſt of iron
gave a great deal of air, two thirds of which was
fixed air, and the reſt was not affected by nitrous
air, and extinguiſhed a candle ; fo that the whole
produce ſeemed to be fixed air, only with a larger
reſiduum than uſual of that part which is not miſ-
cible with water. At another time, however, I got
from the ruſt of iron fixed air that was very pure,
there being little of ic that was not miſcible with
water.
N. B. That part of the ruſt on which the focus
of the lens fell, turned very black.
I obſerved that both the grey calx of lead,
and litharge, yielded fixed air, and that a great
quantity
H
1
Seei. IT.
81
OBSERVATIONS ON FIXED AIR. .
quantity of fixed air is contained in red ledd, and
in other preparations of that metal.
I got a little air by means of the burning lens in
quickſilver, from cinnabar prepared with antimony;
but not enough to form a judgment of the quality of
it. From common vermillion I got more air, viz.
about forty times its own bulk, and it was all fixed
air, being readily abſorbed by water. This ſub-
ſtance, like the ruſt of iron, turned black in the
focus of the lens.
SECTION II,
.
Air from faline Subſtances.
MOST
OST faline ſubſtances, I believe, contain
more or leſs fixed air ; and it may be worth
while to examine what quantity of it may be ex-
tracted from each of them, and alſo the quality of
. the reſiduum, which I find to differ conſiderably in
different cafes. But this may depend, in a great
meaſure, upon the ſtate of the water in which the
experiments are made. A few obfervations that I
VoI.
G
have
1
SE
Part II.
OBSERVATIONS ON FIXED AIR.
*
have had occaſion to make of this kind may be juſt
worth noticing
Both vitriolated tartar, and Glauber ſalt, which I
have often occaſion to make in the courſe of
my
experiments, I find contain fixed air. Diffolving a
quantity of vitriolated tartar, which was formed in
making ſpirit of nitre, and collecting the air that
came from it, I found one twelfth of it to be fixed
air and with an equal quantity of nitrous air, the
meaſures of the teſt for the remainder were 1.3.
At another time I filled the retort in which the ſalt
was contained with boiled pump water, and then I
found no fixed air in it; having, I ſuppoſe, been
abſorbed by the water, and the meaſures of the teſt
for the remainder were 1.46. Again I diſſolved a
quantity of this falt in pump water, and then found
one fourth of the whole to be fixed air ; the pump
water itſelf containing a good deal, and the meaſures
for the reſiduum were 1.44.
From half an ounce of vitriolated tartar, in a gun-
barrel, I got about an ounce-meaſure and a half
of air, which was chiefly fixed air. The laſt pro
duce diminiſhed common air a little ; but this I
attribute to the, gun-barrel not having been per-
fectly cleaned from the materials yfed in a former;
experiment.
Cizi
I alſo diſſolved a quantity of Glauber falt; which
remained from the proceſs for making ſpirit of-falt,
.[
:;?
1
wand
Seet. If.
83
OBSERVATIONS ON FIXED AIR,
ri
and I found the reſiduum of the fixed air to be fen-
ſibly worſe than common air.
• The firſt experiment that I made upon alum,
was with the ſun-beams, in quickſilver; when I
got from it. a little air, which appeared to be
fixed air, by extinguiſhing a candle, and by being
readily abſorbed by water. I repeated the experi-
ment with the faine reſult. The quantity of air
extracted from a piece of alum, was about one third
of its bulk; but I imagined that a little, though not
much, more might have been extracted, by a longer
continuance of the operation.
I obſerved, upon this occaſion, that I could cal-
cine only a given quantity of alum in a given quan-
tity of air ; and that when this was ſaturated, I could
only keep the alum in a fluid ſtate by heat. But it'
was eaſily calcined in vacuo; and as the receivers in
which the calcination was made became very moiſt,
it is
pretty
evident that this operation is performed
by the mere expulſion of the water which enters into
the compoſition of this falt; ſo that when the ſur-
rounding air can take no more water, that calcination
can proceed no farther. I alſo obſerved, upon this
occaſion, that when I had calcined a quantity of alum
in a given quantity of common air, the air was not
diminiſhed, or in the ſmalleſt degree injured, by the
operation.
G2
After
1
84
Part H.
DESERVATIONS ON FIXED AIR.
5
After this, I endeavoured to get air froin calcined
alum, with a burning lens; and I did get a little :
but I made no other obfervation upon it, than that
it was not diminiſhed by nitrous air. But when
I put a quantity of calcined aluin into a gun-barrel,
I
got
froin it a conſiderable quantity of air, part of
which was fixed air, precipitating lime in lime-wa-
ter, and the remainder did not differ from the reſi-
duum of fixed air, extinguiſhing a candle, and
neither affecting common air, nor being affected
by nitrous air.
N. B. The pure air from the alum; and the
inflammable from the iron of the gun-barrel, would
produce the fixed air.
In diffolving alum, in order to get ſome earth
of alum, I obſerved that air was diſcharged from it.
This I collected, and found it to contain very little
fixed air, and the meaſures of the teſt for the reſidu-
um were 1.12. At another time I had the ſame
reſult, but the air was not quite ſo good, though
purer than common air.
Precipitating a ſolution of alum with pot alh, I
caught the fixed air, which was diſcharged in great
abundance; and examining the reſiduum, found it
to be better than common air, in the proportion of
1.2 to 1.3; the diminution being in that propor-
tion when mixed with equal quantities of nitrous air.
From
2
Seet, II,
85
OBSERVATIONS ON FIXED AIR.
From one ounce of calcined alum, very white and
clean, I got fixty ounce meaſures of air, without
any fixed air, or the leaſt imaginable, and ſo
pure,
that with two equal meaſures of nitrous air, the
teſt was 1.40
Still the reſiduum had an acid taſte,
ſo that with more heat, it is probable that more,
and purer air, would have been produced.
The metallic falts, if they gave any air at all, gave
fixed air, which I find to be contained in moſt faline
ſubſtances. I ſhall recite a few experiments of tủis
kind, without any particular regard to the order of
them.
I could get no air whatever from fugar of lead, or
from nitre of lead. The former melted into a liquid
ſubſtance, the latter changed from white to a dull
grey colour, and broke into powder, with a crack-
ling noiſe.
All the kinds of copperas gave fixed air. I firſt
tried common green copperas in quickſilver. It dir-
folved into a great quantity of water, but the air
produced from it was not one twentieth of its bulk.
Half of this air was readily abſorbed by water, and
the remainder was too {mall to be examined. I repeat-
ed the experiment on calcined copperas, both in a gun-
barrel, and likewiſe in a tall glaſs veſicl filled with
fand; but the produce, in all the caſes, was fixed
air. Half an ounce of calcined copperas yielded
near a pint of air.
G3
When
86
Part I).
OBSERVATIONS ON FIXED AIR:
:
$
When I had extracted air from the calx of green
copperas in a glaſs-veffel, I put the faine materials
into a gun-barrel; but ſtill I extracted nothing from
them beſides fixed air, mixed with acid afr, as appear-
ed by the extremely ſmall bubbles to which the large
ones were preſently reduced in paſſing through water:
When I made the experiment on blue vitriol,
which conſiſts of oil of vitriol and copper, in qóick-
ſilver, the reſult was the ſame as with the green cop-
peras, except that much leſs water was produced.
White vitriol, which conſiſts of oil of vitriol and
zinc, gave ten tiines as much air as the other kinds.
Half of it was abſorbed by water, and a candle burn-
ed in the remainder.
Mercurial nitre gave a great quantity of air in
quickſilver, and this was pure nitrous air ; but pof-
ſibly the nitrous acid being let looſe from this ſub- ·
ſtance, had produced the nitrous air by diffolving
the quickſilver.
White lead yielded air' in great plenty, by the
heat of the burning lens, and it was all pure fixed air. .
From four ounces of white lead I expelled, in an
carthen retort, 240 ounce meaſures of air, before the
retort was diffolved by it. Of the firſt produce there
remained one third, not fixed air, of the ſtandard of
1.36; and towards the laſt, the reſiduum was of the
ſtandard of 1,28, when with the common air it was
1.23
SEC
1
SEET. ITL
87
OBSERVATIONS ON FIXED AIR.
!
+
SE C T I O N III.
Air from Subſtances of a vegetable Origin.
ARTAR is a ſubſtance concerning which
there has been a great diverſity of opinions
among chemiſts. On this account ſome of my che-
mical friends requeſted that I would examine what
kind of air it yielded in different circumſtances.
Accordingly, to ſatisfy them, and my own curioſity
at the ſame time, and without any particular ex-
pectation (for I had formed no opinion whatever
avith reſpect to it) I began with putting a finall
quantity of the cream of tartar into ſome oil of vi-
triol, contained in a phial with a ground ſtopper and
tube (which is the method that I uſually employ to
procure-vitriolic acid air) and, with the flame of 2
candle, I made it boil.
The acid preſently became black, and the mix-
ture yielded a great quantity of air, till it was quite
viſcid; when, there being fome danger of choaking
the tube, I withdrew it. The air was at firſt half
fixed air, making lime water turbid, and half in-
flammable, burning with a lambent blue Aame ;
but towards the laſt two thirds of it was inflamma-
ble. I did not uſe more than a few penny-weights
1
G4
of
88
Part II,
OBSERVATIONS ON FIXED AIB.
of the tartar, and the quantity of air exceeded two
quarts, and much more might certainly have been
procured. The next day the matter, which I had
poured out of the phial, had the conſiſtency, co-
lour, and ſmell of treacle; except that there were
ſome ſmall concretions in it. Some time after ]
took the reſiduum above-mentioned, and putting it
into a glaſs veſſel, I again extracted from it, in a
fand heat, a large quantity of air, as much as before,
and exactly of the ſame kind. In the middle of
the proceſs, when the production of air was moſt
copious, it was very turbid; and when any of the
bubbles burſt in the open air, they were perceived
to have a ſtrong ſmell of treacle.
After this I ceaſed to make uſe of oil of vitriol,
in order to try what air the tartar would yield of it-
felf; and I preſently found that the acid had con-
tributed nothing at all to the air that I had got from
it. From an ounce of cream of tartar, in a glaſs
veſſel, and a fand heat, I got 170 ounce meaſures
of air, the firſt portions of which .were almoſt pure
fixed air. The reſiduum, however, was inflam-
mable, and burned with a blue flaine. At laſt
only about two thirds of the air was fixed air, and
the reſt inflammable. In the greateſt part of the
proceſs, the air was very turbid; but it was fo in the
recipient, and the part of the tube next to it, a con-
fiderable time before it was turbid in the reſt of the
tube,
1
SeEZ. III.
89
OBSERVATIONS ON FIXED AIR.
0
tube, or in the glaſs veſſel that contained the ma-
terials. Towards the end of the proceſs the em-
pyreumatic oil came over, which was very offenſive,
though, at firſt, the ſmell of the air had been rather
pleaſant, reſembling that of burnt ſugar.
I repeated this experiment, and again got about
170 ounce meaſures of air from an ounce of cream
of tartar, of which thirty eight ounce meaſures were
inflammable, and the reſt fixed. It burned with a
large white flame, but at laſt with a light blue one,
owing, I ſuppoſe, to the mixture of fixed air in it.
That cream of tartar ſhould yield fixed air will
not be thought extraordinary; but its yielding in-
flammable air, ſeems to fhew that it had acquired a
good deal of the conſiſtence of vegetable matter, or
of pit-coal, ſince thoſe ſubſtances yield the ſame kind
of air.
After this, neglecting the produce of air, I ſim-
ply calcined a quantity of cream of tartar, in a red
heat, in a glaſs veſſel filled up with ſand; and ob-
ſerved that it loft about half its weight. Notwith-
ſtanding its calcination in a red heat, this ſubſtance
obſtinately retained a great deal of its fixed air, in
which it reſembles chalk. For when I put this cal-
cined cream of tartar into ſpirit of ſalt it yielded a
conſiderable quantity of air, which I found to be
fixed air, with a phlogiſticated reſiduum. It alſo,
efferveſced in the ſame manner, and no doubt gave
che
90
Part II.
OBSERVATIONS ON FIXED ATR.
L
Į
the ſame kind of air in oil of vitriol, and ſpirit of
nitre. But even fpirit of ſalt did not diſſolve the
whole of it.
To obſerve the phenomena of this calcination
more particularly; I made the proceſs in an open
crucible, which I kept in a red heat: a long time.
But alien there was no appearance of any. farther
change; and the ſubſtance was pretty:hard; I took it
from the fire, on which it prefently aſſumed a black-
iſh, or dirty brown colour. Spirit of ſalt diffolved
this ſubſtance with as much rapidity, to all appear-
ánce, as it had done the mere black coal of tartar
in the former experiment, and expelled as much
air from it. It ſtill, however, did not diffolve
the whole : for a dirty powder remained undif-
folvech
I threw the focus of the lens upon a piece of fine
white Tigar, "in quickſilver. It was readily melted
and converted into a brown ſubſtance, yielding about
two thirds of its bulk of air, one third of which was
readily abſorbed by water, and the remainder extin-
guiſhed a candle. I repeated the experiment with
a browniſh powdered ſugar, with the ſame reſult,
excepting that more air was generated from this
than from the white ſugar, in proportion to their
bulks.
From two ounces and three quarters of wood
albes I got, in a very ſtrong heat, 430 ounce mea-
furcs
Sect. III.
91
OBSERVATIONS ON FIXED AIR.
ſures of air, of the firſt portion of which one tenth,
of the ſecond one third, and of the third one half
was fixed air. The reſiduum of the ſecond
por-
tion was of the ſtandard of 1.6, and that of the
third 1.7. It extinguithed a candle; fo that the
air came. properly from the aſhes, and not from
any remaining particles of the charcoal mixed with
them. After the proceſs, the aſhes weighed.839
grains. Being expoſed to the open air one day,
they weighed 842 grains, and, perhaps with more
heat than before, yielded fifty ounce meaſures of
air, of which about an eighth was fixed air, and the
ſtandard of the reſiduun was 138, and 1.41. A
candle burned in it; ſo that it is evident fome of
the deplogiſticated part of the atmoſphere had
been imbibed by theſe aſhes. They then weighed
789 grains and a half.
From three ounces of pit-coal aſhes, I got air,
the ſtandard of which was 1.7, and extinguiſhed a
candle. I took no note of the quantity of fixed
air, and through an accident in the proceis moſt
of the air eſcaped.
It is well known that all
. fermented liquors,
that are not quite flat or vapid, contain fixed air;
and I had the curioſity to try, what proportion of
this air is concained in different kinds of wine,
and in wines in different ſtates. For this purpoſe,
I took one of the phials with a ground-ſtopper and
tube;
92
Part II.
OBSERVATIONS ON FIXED AIR.
!
tube, containing an ounce-meaſure and a half,
and filling it accurately with each ſpecies of
wine, I plunged it into a veſſel of water, which
was ſet on the fire to boil, receiving the air in
quickſilver. The air that I got from all kinds
of fermented liquors was pure fixed air; but,
except champaigne and cyder, it was in inuch
lèſs quantity than I expected; the reſults being as
follows.
W
The quantity of air contained in
Madeira, was
Too of an ounce-meaſure.
Port of ſix years old 28
Hock of five years old ร
Barrelled Claret
Tokay of ſixteen years at
Champaigne of two years 2
Bottled Cyder of 12 years 34
Some champaigne ſparkles much in conſequence
of containing much air; but there is a kind of
champaigne which does not ſparkle, and contains
very little air. The difference, as I was informed,
when I made enquiry concerning it, in that part
of France where the wine is made, is owing to
this; that when they wiſh to have the wine ſparkle,
they check the fermentation as much as poſſible
at the time that the wine is made ; ſo that the
ſerinentation going on gradually, the fixed air fro-
duced
g
+
Sect. III.
93
OBSERVATIONS ON FIXED AIR.
1
duced by it is abſorbed by the liquor: whereas,
when they do not chuſe to have it ſparkle, they
let it ferment freely, like any other kind of wine.
In other caſes, therefore, where fermented liquors
contain much air, as in moſt kinds of malt-liquor,
cyder, and our Engliſh made-wines, I take it for
granted, that the fermentation is either purpoſely
checked, or that the liquor is of ſuch a nature,
that the fermentation will neceſſarily continue a
long time, after it is put into the caſk or bottle.
I once found that a quantity of port-wine con-
tained its own bulk of fixed air; but I now ima-
gine that the wine was not genuine, but muſt have
been made chiefly of cyder. Perhaps this may
not be a bad method of diſtinguiſhing genuine
foreign wines from compoſitions made of cyder.
1
1
SEC.
94
Part It
OBSERVATIONS ON FIXED AIR,
SECTION IV.
Air from Animal Subſtances.
I
Had obſerved, that animal ſubſtances, in putre-
fying, diſcharge air that is in part fixed, and
part inflammable. Being willing to find the pro-
portion of each of theſe kinds of air, in the different
ſtages of the putrefactive proceſs, as well as the
whole produce of both kinds, I took a piece of the
lean muſcular part of mutton, weighing 102 grains,
on the 13th of September, 1776, and put it into
a jar filled with quickſilver, ſtanding inverted in
a baſon of the ſame, and placed it near the fire,
where the heat was variable, but at a medium of
about 100 degrees of Fahrenheit.
On the 15th I took from the mutton half an
ounce meaſure of air, two thirds of which was
fixed air, making lime-water turbid, and the reſt
was ſtrongly inflammable. On the 16th it had
yielded one third of an ounce meaſure of air, of
which the fixed air and the inflammable were ex-
actly in the ſame proportion to one another as
before, but the inflammable air at this time was
all fired at one exploſion, and without that redneſs
in
Seet. IV.
95
OBSERVATIONS ON FIXED AIR.
in the flame that I had perceived before. On the
19th I took from it about half an ounce meaſure
of air, three fourths of which was fixed air, and the
reſt inflammable.
After this I removed the mutton and quick-
filver into the common temperature of the atmoſ-
phere, where they continued to the 13th of January
following, in all which time very little was added
to the air that had come from it before its removal.
I then, however, took from it half an ounce mea-
ſure of air, and it was all pure fixed air, without
the mixture of any thing inflammable in it. Then
placing it near the fire as before, it preſently yield-
ed another half ounce meaſure of air, which was
alſo wholly fixed air.
Obſerving that it ſtood near twenty-four hours
after this without producing any more air, though
it was in the ſame degree of heat, I plunged the
whole into a pan of water, and made it boil; by
which means I got from it about one eighth of an
ounce meaſure of air, the whole of which was
fixed air; at leaſt the reſiduum was not larger
than is uſual in pure fixed air ; for it was too ſmal :
a quantity to make an experiment upon with the
fame of a candle. After this I kept it in a boil.
ing heat a conſiderable time, without getting from
it any air at all.
It appears therefore, that this
piece of mutton yielded in all 24 meaſures of air,
1
! i
of
96
Part II.
OBSERVATIONS ON FIXED AIRY
of which 236 was fixed, and the reſt inflammable,
and that all the inflammable part was exhauſted a
conſiderable time before the fixed air.
On the 13th of March, 1780, I took two dead
mice, of about equal ſize, and put them into two
ſeparate cups, under different jars of common air;
of very nearly equal capacities, one of them con-
taining 155 ounces of water, ſtanding in quick-
ſilver, and the other 160 ounces, ſtanding in water.
Leaving them in the country to the care of a
perſon who ſupplied the veſſels in which they ſtood
occaſionally with water or quickſilver, I went to
London, and after my return, in the beginning of
Auguſt, I found, by marking the veſſels, and mea-
furing them afterwards, that the air in the veſſel
which had ſtood in water was reduced to 140
ounce meaſures; and on the 28th of Auguſt it
was reduced to 135, but after ſtanding a fortnight
longer, it was not ſenſibly diminiſhed any farther.
The air in the veſſel which had ſtood in quick-
ſilver was not ſenſibly diminiſhed at all.
Admitting lime water to this veſſel, it preſently
became turbid; but this being a now diminution
I removed the veffel after ſome days to a trough
of water, and then found that the air contained in
it made lime water exceedingly turbid; and agitating
this air in ſmall portions it was preſently reduced
10 125 ounce meaſures; fo that all the quantity
diminiſhed
t
1
4
Sect. IV:
OBSERVATIONS ON FIXED AIR.
97
diminiſhed ſeems to have been fixed air, making
lime water turbid, and being abſorbed by water in
the very fame manner.
:
The air in the veſſel which had ſtood in water,
notwithſtanding the opportunity there was for the
fixed air depoſited by it being readily abſorbed,
made lime water very turbid; and by agitation
in ſmall portions this air was reduced to 130 ounce
meaſures. Upon the whole it appears, that
the diminution in both of theſe caſes was nearly
equal, viz. a little more than one fifth.
In theſe experiments the two mice were thorough-
ly putrefied, and indeed quite diffolved, and no
doubt had yielded all the air they were capable of
yielding. But if the experiments on the putrefac-
tion of mice in quickſilver recited above be com-
pared with theſe; it will be found that the addition
of fixed air, or air of any other kind, from the
putrefied mice was quite inconſiderable, viz. an
ounce meaſure and half of fixed air, and half an
ounce meaſure of inflammable from each.
It is true that mice putrefying in water yield
perhaps more fixed air than in this proportion;
but here they putrefied in air only. And that a
very inconſiderable quantity is produced in theſe
circumſtances, is evidenc from there being little
or no increaſe of the air when it is confined by
quickſilver, which could not imbibe fixed air, if
VOL. I.
H
any
!
98
Part II.
OBSERVATIONS ON FIXED AIR.
1
any had been diſcharged from the putrefying
mice. It will be found hereafter, that water is a
neceſſary ingredient in the conſtitution of both fixed
and inflammable air.
It might be queſtioned, whether the fixed air
contained in our aliments, can be conveyed by
the courſe of circulation into the blood, and by
that means impregnate the urine. I have found,
however, that it may do it; having more than
once expelled from a quantity of freſh-inade urine,
by means of heat, about one fifth of its bulk of
pure fixed air, as appeared by its precipitating
lime in lime water, and being almoſt wholly ab-
forbed by water; and yet a very good air-pump
did not diſcover that it contained any air at all.
It muſt be obſerved, however, that it required
ſeveral hours to expel this air by heat; and after
the proceſs, there was a conſiderable whitiſh ſedi-
ment at the bottom of the veſſel. This was, pro-
bably, fome calcareous matter with which the
fixed air had been united; and by this fixed air,
the calcareous matter, which would otherwiſe have
forined a ſtone or gravel, may have been held in
ſolution; and therefore, drinking water impreg-
nated with fixed air, may, by iimpregnating the
urine, enable it to diſſolve calcareous matters bet-
ter than it would otherwiſe have done, and may
therefore be a means of preventing or diffolving
the
!
F
1
Sect. IV.
99
OBSERVATIONS ON FIXED AIR.
1
the ſtone in the bladder, agreeable to the propoſal
of my friend Dr. Percival.
From four ounces of dry ox blood I got 1200
ounce meaſures of air, and I conjectured that not
leſs than 200 ounce meaſures eſcaped. It con-
tained no fixed air. The firſt portion of it burned
with a large lambent white flame, the middle por-
tion fainter, and the laſt was hardly inflammable
at all, but had a ſlight blue flame. What remain-
ed of the blood weighed 255 grains, and was, a
very good conductor of electricity, which is not
uſually the caſe with the charcoal of animal ſub-
ſtances.
H2
PART
100
Part. III,
OBSERVATIONS ON FIXED AIR.
PART III. .
VARIOUS PROPERTIES OF FIXED AIR.
SECTION
I.
The Effects of fixed Air on Animals and Vegetables.
NSECTS and animals which breathe very
INS
little are ſtified in fixed air, but are not ſoon
quite killed in it. Butterflies, and Aies of other
kinds, will generally become torpid, and ſeem-
ingly dead, after being held a few minutes over
fermenting liquor; but they revive again after
being brought into the freſh air.
But there are
very great varieties with reſpect to the time in
which different kinds of flies will either become
torpid in the fixed air, or die in it.
A large
ſtrong frog was much ſwelled, and ſeemed to be
nearly dead, after being held about ſix minutes
over the fermenting liquor; but it recovered upon
being brought into the common air. A ſnail
treated in the ſame manner died preſently,
While
)
Sect. I.
IOI
OBSERVATIONS ON FIXED AIR.
/
While I was making experiments on the fixed
air produced by the fermentation of beer, in a
public brewery, which was a conſiderable time be-
fore I attempted to procure it in any other man-
ner, I had the curioſity, among other things, to
try what effect it would have on the vegetation of
plants, and the colours of fome delicate flowers;
both which I could eaſily ſuſpend within the region
of fixed air over the fermenting vațs. The reſult
of a few experiments, which I made in theſe cir-
cumſtances, was as follows.
Fixed air is preſently fatal to vegetable life.
At leaſt ſprigs of mint growing in water, and
placed over the fermenting liquor, will often
become quite dead in one day; nor do they
recover when they are afterwards brought into the
cominon air.
I am told, however, that ſome
other plants are inuch more hardy in this reſpect.
A red roſe, freſh gathered, loſt its redneſs,
and became of a purple colour, after being held
over the ferimenting liquor about twenty four
hours; but the tips of cach leaf were much
more affected than the reſt of it. Another. red
roſe turned perfectly white in this ſituation : but
various other Aowers, of different colours, were
very little affected.
Theſe experiments were
not then repeated, as I wiſhed they might be done,
.
H 3
in
102
Part III.
OBSERVATIONS ON FIXED AIR.
ino
in
pure
fixed air, extracted from chalk by means
of oil of vitriol.
After this I found a contrary opinion to prevail
,
viz, that fixed air is ſo far from being deſtructive
to vegetation, that it is the proper pabulum of ve-
getables; making them to flouriſh much more
than they could do in other circumſtances; and
that, inſtead of diſcharging the colour of roſe leaves,
it is a means of preſerving them, and all other
moſt delicate flowers, in thợ greateſt perfection. I
therefore made the following experiments.
On the 5th of June, 1776, I put two ſprigs
of mint into two equal jars, filled to the fame
height with pure fixed air, extracted from chalk
by oil of vitriol, the lower parts of each jar con-
taining equal quantities of the ſame rain water;
with this difference, that into one of the jars I con-
veyed a little oil, to prevent the too quick abſorp-
tion of the fixed air by the water. Alſo in the
ſame trough of water, in which ſtood the jar with-
out oil, I placed another jar, filled to the ſame
height with pure fixed air, without any plant. I
preſently obſerved that the water roſe in all the
jars exactly alike, except in that which had the oil
on the ſurface of the water; and the next morn-
ing both the plants appeared to be quite dead,
their ſtems and leaves having became almoſt black
and
1
1
1
7
Sect. I.
IO3
OBSERVATIONS ON FIXED AIR,
+
and flaccid. After two days, when there was evi-
dently no probability of the plants recovering them-
ſelves, I took them out, and found the air to which
they had been expoſed not in the leaſt changed, be-
ing juſt as much abſorbed by water as other' fixed
air.
Thinking it poſſible, that though theſe plants
died in a toral change of atmoſphere, they might,
notwithſtanding, have borne a partial charge of it, I
took three other plants, and put one of them into a
jar of air of which two thirds, another into one of
which one half, and a third into one of which one
fourth was fixed air. But, to all appearance, all
theſe plants died as quickly as the two former had
done, which I believe was, in fact, almoſt inſtantly:
for the ceffation of vegetable life muſt have con-
ſiderably preceded ſuch viſible effects of it as the
blackneſs and faccid ſtate of the leaves and ſtalks.
To cloſe this fet of experiments, I, in the laſt place,
put only one eighth part of fixed air to two plants
which had been growing ſome time very well in
phials of water, over which I had placed jars full of
common air only, in order to avcid wetting the
plants, or doing them the least imaginable inj
in any reſpect. But, notwithitardirg this, and
though very little indeed of the fixed air could be
ſuppoſed to remain a long time, of ſo very ſmall :
quantity, expoſed to fo very large a ſurface of wa-
ter,
н H A
+
:
1
litt
104
OBSERVATIONS ON FIXED AIR, Part III.
.
ter, in a few days the tips of the leaves, even to the
tops of the plants, turned black : both of them foon
ſhewed evident marks of decay: one of them died in
about ten days, and the other did not ſurvive more
than about three weeks. For in ſuch a languiſhing
ſtate, it is not eaſy to ſay at what preciſe time a plant
muſt be pronounced to be properly dead.
In the next place I tried the effect of water im-
pregnated with fixed air on the roots of plants.
In one caſe, a ſprig of mint, in the impregnated
water, grew better than a ſimilar plant in the ſame
water not impregnated with fixed air ; but another
plant grew much worſe than its companion in
common water. Beſides, though it ſhould appear
that, for a time, a plant ſhould grow better in this
kind of water, it may, perhaps, be attributed to the
effects of ſtimulus only, which is not peculiar to fixed
air, but might reſult from the action of any other
acid. And when I put a little coinmon ſalt, or
even a little ſpirit of nitre into the water in which
the plants were growing, I imagined that, for ſome
time, it rather promoted their growth. Alſo, though,
in general, plants die almoſt immediately in water
impregnated with nitrous air, yet in one caſe of this
kind, when the ſuperfluous nitrous air was carefully
let out under water, ſo that no part of it was de-
compoſed in contact with the water, the plant grew
in it remarkably well.
The
1
1
1
SeEt. I.
OBSERVATIONS ON FIXED AIR.
IOS
1
The few obſervations that I have made on the
growth of plants in water impregnated with fixed
air, but which I do not pretend to be ſufficient to
decide the queſtion, were the following. On the
20th of Auguſt 1776, I gathered two ſlips of mint,
and likewiſe two ſmall plants of the fame kind, with
roots; of which I put one of each kind into an eight-
ounce phial of rain-water, and the others into other
ſimilar phials, filled with the fame water impreg-
nated with fixed air ; putting at the mouth of each
of them a little ſoft clay, to prevent the too eaſy
eſcape of fixed air from thoſe that contained it, and
to put the others, as nearly as poſſible, into the ſame
circumſtances.
For ſome time all theſe plants appeared to flouriſh
equally well ; but after a week it was evident that
the ſlip of mint in the impregnated water, grew
better than its companion. On the 4th of Septem-
ber the plant in the ſimple water was in a dying
condition, and the other began ſenſibly to languiſh,
and was dead, I think, about a week after the
other.
The two plants with roots grew very well ; but
that in the ſimple water much better than the other ;
and more of the water had been exhaled from the
phial, the reverſe of which had been the caſe with
the ſlips. On the 24th of September the plant in
the fixed air was abſolutely dead ; but the other in
ſimple
4
+
;
106
OBSERVATIONS ON FIXED AIR.
Part III.
fimple water was very flouriſhing on the 28th,
when I put an end to the experiment. Examining
the phials of impregnated water, I found that nei-
ther of them had intirely loſt its fixed air. That
in which the ſprig of mint had grown, ſtill con-
tained one ſixth of its bulk of fixed air, and the wa-
ter in which the plant with its root had grown,
which was a much longer time, retained, however,
one twelfth of it.
To try the effect of different ſtimuli on the roots
of plants, I firſt put into phials containing an ounce
meaſure and a half of common water, ſmall
quantities of common falt, from one grain to twelve;
and more. In all thoſe which contained more than
twelve grains, the plants died immediately, but in
that phial the plant lived a fe:v days; and the reſt
died, in their order, to that which contained three
grains of falt, which ſeemed to grow as well as the
plant in ſimple water. And it was remarkable that
not only this plant, but alſo thoſe which had died
ſeemed to flouriſh more at the firſt, than thoſe which
grew in ſimple water : and that which had three
grains of ſalt, and alſo that which had one grain,
continued to live after the plant in ſimple water was
dead in the ſame room. This was in my laboratory,
a place unfavourable, indeed, to any vegetation, but
equally fo to all
Sprigs
A
Sect. I.
107
OBSERVATIONS ON FIXED AIR.
1
Sprigs of mint in one and a half ounce phials, con-
taining one, and even two'drops of the ſtrongeſt nitrous
acid Aouriſhed very well, better, ſeemingly, than
thoſe in mere water ; but in water containing more
of this acid, they died inſtantly.
I am far from pretending that theſe few experi-
ments on the vegetation of plants in water impreg-
nated with fixed air, are deciſive; but I think they
ſhew that a very great number of experiments, and
thoſe uniform in their reſult, are neceſſary to deter-
mine this queſtion. When fome plants grow bet-
ter, and ſome worſe, it makes it probable that the
difference in the growth depends upon ſome other
circumſtance than the water in which they grow.
While I was attending to the compariſon of the
growth of plants in dephlogiſticated and common
air, I at the ſame time made a few farther experi-
ments on the growth of plants with their leaves
expoſed to fixed air, though I was pretty well ſa-
tisfied, from the experiments recited above, that
this kind of air is undoubtedly injurious to plants
growing in it. I wiſhed alſo, once more, to try
the effect of inflammable air, with reſpect to vege-
tation.
Accordingly, in the month of April 1777, I
introduced a ſprig of. mint into a phial of air, one
third fixed and the reſt common; and having only
once ſupplied it with freſh fixed air (when the bulk
of
108
Part III.
OBSERVATIONS ON FIXED AIR.
of the former was abforbed by the water) I obſerv-
ed, that on the 3d of May following, there were
black ſpecks on ſeveral of its leaves, and in the
courſe of a week it was almoſt wholly black, and
evidently dead. It had not grown at all.
At the ſame time I put another ſimilar plant
into a jar of half freſh made inflammable air and half
common air, but it died preſently. I found, how-
ever, by ſubſequent trials, that plants would bear
a greater proportion of inflammable than they would
of fixed air ; fo that from the circumſtance of plants
merely living in a proportion of fixed air, it cannot
be inferred that it is of itſelf, at all favourable to
their growth.
The few experiments that I had an opportunity
of making before, left me altogether undecided
with reſpect to the effect of water impregnated with
fixed air on the roots of plants. But the many ex-
periments that I have made ſince, in 1777, and
1778, have not left a ſhadow of doubt on my mind,
that ſuch water is hurtful, and finally fatal to the
plants growing in it, at leaſt to ſprigs of mint ; for
I did not make the trial with any other plants.
On the 28th of May I placed, in a green houſe,
and not in my laboratory, as in the experiments
mentioned before, three ſprigs of mint, with
their roots in phials of water impregnated with
fixed air, and three other plants of the fame kind
with
*
1
no
Seef. 1.
OBSERVATIONS ON FIXED AIR.
109
1
with their roots in the ſame water unimpregnated.
After a week I changed the impregnated water, on
account of the mouths of the phials being left open,
leſt the plant ſhould have been injured by putting
any thing about them, to prevent the eſcape of the
air from the water.
During two or three days at the firſt, the plants
in the impregnated water were more vigorous than
the others; but on the 8th of June following, they
all looked much worſe than thoſe in the common
water. Alſo thoſe in the common water had long
white filaments ſhooting from their roots, whereas
thoſe in the impregnated water had none of them.
On the 18th of June, the plants in the impregnated
water were all quite dead, their leaves having all
fallen off one after another, beginning at the bot-
tom. Examining one of the phials, I found that it
contained between one fifth and one ſixth of its bulk
of fixed air.
I repeated theſe experiments ſeveral times in
the courſe of that ſummer, generally uſing many
more plants than in theſe laſt mentioned, but the
reſult was the fame in them all. However, as it
generally happened, on what account I cannot tell,
that the plants in the unimpregnated water died;
though later than the others, I deferred the laſt
and deciſive trial till the year following, after which
I had no doubt remaining on the ſubject.
On
IIO
Part IIT:
OBSERVATIONS ON FIXED AIR.
On the 4th of May, 1778, I put ſeven ſprigs
of mint into pump water impregnated with fixed
air, and ten or twelve in the ſame water unimpreg-
nated, the phials being ſimilar, and I placed them
all in a ſummer houſe, in the ſame expoſure. I
renewed the impregnated water every week, till
the 23d of June, when all the plants in the water
impregnated with fixed air were dead, the roots
being black and rotten; while the other plants were
in as flouriſhing a ſtate as poſſible, and continued
to flouriſh long after, till I diſcharged the ex-
periment.
. On this occaſion I did not obſerve that the
plants in the impregnated water were at any timė
more flouriſhing than the others, not even at the
beginning; and after'a fortnight the difference in
appearance, to the diſadvantage of thoſe in the
impregnated water, was very viſible. Thoſe which
grew in the common water threw out inany white
filaments from their roots, many of thein ſo long
as quíte co fill the phial, twiſting themſelves in all
directions, and exhibiting a very beautiful appear-
ance; whereas there was nothing of this kind in
any of the phials of impregnated water. On the
contrary, the roots becaine preſently. black, and at
length rotted quite away.
One of theſe I had overlooked, and had neg-
lected to change the water; and this plant threw
)
1
2
out
+
Sect. l.
III
OBSERVATIONS ON FIXED AIR.
out a few white filaments; but, on renewing the
impregnated water, they preſently became black
and periſhed.
It was remarkable alſo, that two of the plants
in the impregnated water threw out thick knots
of thoſe white filaments in the necks of the phials,
juſt above the ſurface of the water, but not one
of them within the water itſelf, or ever entered
the water. Alſo, when I took one of theſe plants,
the roots of which were quite perihed, out of the
impregnated water, and put it into a phial of com-
mon water, it threw out new white roots above
the place that was decayed, and afterwards
grew
very well.
Mr. Hey, of Leeds, palling through Calne,
where I then reſided, happened to ſee theſe plants
in the laſt ſtage of the proceſs, and thought that
no experiment could be more ſatisfactory.
1
SEC.
112
Part III.
OBSERVATIONS ON FIXED AIR.
SECTION
II.
Of the Change made in fixed Air by the ele&tric Spark.
*
I
Obſerved in a very early period of my experi-
ments, that by taking the electric ſpark in fixed
air, a part of it is converted into air that is not
abſorbed by water. I have ſince repeated this
experiment with more care; and though I have
never been able to make the whole of any propor-
tion of fixed air immiſcible with water by this
means, yet I have always ſo far changed it, that
the reſiduum was more conſiderable than before,
but in different proportions.
I took the electric ſpark about two hours in a
ſinall quantity of fixed air confined in a glaſs.tube
by mercury. Before the experiment, one thirtieth
of the air was unabſorbed by water, but afterwards
one fourth. The glaſs tube, in which this experi-
ment was made became very black in the inſide ;
and as this change is made in mercury by the
addition of phlogiſton, it looks as if ſome of the
phlogiſton, which had made a part of the fixed
air, had, by this proceſs, been ſeparated from it;
and leaving a greater proportion of dephlogiſticated
air
2
1
1
f
.
Sect. II. OBSERVATIONS ON FIXED AIRÓ 113
air in the remainder, would neceſſarily make it leſs
miſcible with water. The blackneſs on the inſide
of the tubes, in which the 'electric ſpark is taken
through vitriolic acid.airior common air I before
diſcovered to be mercury ſuperſaturated with phlo-
giſtón.
The next time that I repeated this experiments
I attended to the quality of the reſiduuin before
and after the proceſs; and the reſult was ſuch as
feems to confirm the above-mentioned conjecture.
I took the electric ſpark an hour and ten minutes
in little more than half an ounce meaſure of fixed
air, after which one fifth of the whole was unab-
forbed by water, and the ſtandard of the reſiduum
Of the original fixed air about one
thirtieth was unabſorbed by water, and the ſtandard
of the reſiduum was 1.0. . In this experiment I
alſo obſerved that the quantity of the air in which
I made the experiment was increaſed about a twen-
tieth
part,
which I do not pretend to explain.
Again, I took the electric ſpark an hour in half
an ounce meaſure of fixed air, after which there
remained as much refiduum unabſorbed by water
as had remained in about five times the quantity
of the ſame fixed air in which no ſpark had been
taken. This reſiduum was alſo much purer than
that of the original fixed air, the ſtandard of it be-
ing 0.8, whereas that of the original fixed air had
VoL, I,
I
been,
was 0.9.
I14
Part III.
OBSERVATIONS ON FIXED AIR.
been, as before, 1.0. I repeated the experiment,
and found the reſiduum ftill greater, but of the
ſame pure quality; and in this caſe I obſerved a
good deal of the black matter adhering to the in-
ſide of the tube.
In the following experiment I obſerved a farther
change in this ſubſtance. In a ſmall tube, con-
taining about one fifteenth of an ounce meaſure of
fixed air, I took the electric ſpark about an hour ;
after which there was a good deal of the black
matter clouding all the inſide of the tube, but the
lower part of it was covered with 'ſomething of a
yellow colour, like ſulphur. In this caſe the re-
fiduum not abſorbed by water was between one
fourth and one fifth of the whole, and leſs pure
than the former reſiduums. Had not the dephlo-
giſticated air in the fixed air paſſed into the mer-
cury, tending to make it a precipitate per fe? Was
not this the cauſe of the reſiduum being leſs pure
than before?. And does not this experiment alſo
prove, that phlogiſticated air may be compoſed of
the fame materials with fixed air, viz. dephlogiſ-
ticated air and phlogiſton?
Again, I took the electric ſpark three hours in
a ſmall quantity of fixed air, and obſerved that it
was firſt increaſed, and then diminiſhed about one
eighth of the whole; the inſide of the tube being
very: black, and below the mercury very yellow,
about
1
:
H
1
1
Selt. II.
OBSERVATIONS OF FIXED AIR.
115
about the ſpace of a quarter of an inch quite round
the tube. But that ſpace, or at leaſt part of it, had
been above the mercury at the beginning of the
proceſs. There remained one third of the air
unabſorbed by water, and ſo impure, that the
ſtandard of it was 1.8.
To vary the experiment, I took the electric
ſpark in a quantity of fixed air confined by water,
impregnated with fixed air The quantity was
much increaſed by the air extricated from the
water, and after the proceſs by far the greater part
of it was incapable of being abforbed by lime water.
In the courſe of this experiment, I obſerved that
water impregnated with fixed air is by no means
ſo good a conductor of electricity as water impreg-
nated with any of the mineral acids.
Again I took the electric ſpark in fixed air,
confined by a little common water, and obſerved
that the blackneſs mentioned above extended more
than a quarter of an inch below the ſurface of the
mercury, in the ſame manner as the yellow colour
had done before. In this caſe alſo, the reſiduum
was purer than that of the original fixed air.
Again I took the electric ſpark half an hour in
feven tenths of an ounce meaſure of fixed air, after
which one tenth of it was immiſcible with water,
and the reſiduum was evidently better than the
natural reſiduum of the fame fixed air. The ſtan-
12
dard
.
116
Part III.
OBSERVATIONS ON FIXED AIR.
dard of that had been 1.0, and of the other
about 0.85.
I took the electric ſpark three hours in about
three fourths of an ounce meaſure of fixed air,
after which it was increaſed in bulk one eighteenth.
Water being admitted to it, there remained one
ſixth unabſorbed. Being examined, the ſtandard
was found to be as before, a little better than the
reſiduum of the fame fixed air*
Being deſirous of aſcertaining whether this change
in the conſtitution of the fixed air was owing to
the light, or the heat produced by the electric ſpark,
or to ſomething peculiar to electricity. I firſt
threw a ſtrong light by means of a burning lens,
on ſome pounded glaſs, confined in fixed air, for
ſome hours. But though the reſiduum was by
this means a little increaſed, yet being of the ſame
quality with the common air, I ſuſpected that it was
the air which was neceſſarily introduced througlı
the quickſilver along with the pounded glaſs.
There was no change in the dimenſions of the air
after the experiment.
I repeated the proceſs with fine glaſs-houſe ſand,
which had been previouſly expoſed to a ſtrong
* The addition of air in theſe experiments, Mr. Monge found to
be inflammable, which muſt have come from the calcination of the
mercury, and not, as he ſuppoſes, from the decompoſition of the
water diffuſed through the fixed air. Mem. De l'Academie des
Sciences for 1786, p. 430.
3
heat
Sect. II.
117
OBSERVATIONS ON FIXED AIR.
heat. But though the reſiduum was increaſed,
the experiment was not, upon the whole, more
ſatisfactory than the former. I alſo heated bits of
crucibles in the ſame manner, and found the re-
ſiduum larger than before, in the proportion of
10 to 6.6; but the quality of it was worſe. To
what this ſhould be owing, I cannot tell.
I once more repeated the experiment with bits
of crucibles, and the reſult was certainly favourable
to the hypotheſis of a real change being made in
the quality of the air by beat, but I do not pretend
to ſay: that it was deciſively ſo. After the proceſs
with fifty ſix meaſures of the air there was a re-
fiduum of three meaſures; whereas before the ex-
periment, the ſame quantity of the fixed air had
left a reſiduum of only two meaſures. And that
the additional meaſure was not the common air,
introduced into the veſſel by adhering to the bits
of crucibles, was evident from the quality of the
reſiduum, which was the very fame, viz. of the
ſtandard of 11. I alſo aſſured myſelf that there
was no fallacy of this kind in the experiment, by
introducing the very fame bits of crucibles into
another equal quantity of fixed air. For I did
not find that any ſenſible quantity of common air
had been carried into the veſſel along with them.
However, by heating iron in fixed air, there
can be no doubt but that a ſenſible quantity of it
is converted into phlogiſticated air; which agrees
I3
with
IIS
Part III.
OBSERVATIONS ON FIXED AIR.
+
with the experiments that I formerly made by
putting pots of iron filings and brimſtone into fixed
air. The experiments that I made of this kind
were the following, in which it will be obſerved,
that, though in ſome of them, there was an in-
creaſe of the quantity of air after the proceſs, yet
that it was by no means equal to the quantity that
remained, unabſorbed by the water; and there.
fore, there muſt have been a farther addition made
of this kind of air in the proceſs.
After heating turnings of malleable iron in a quan-
tity of fixed air for ſome time, I examined a part
of it, and found that about one tenth of the whole
was immiſcible with water. Having reſumed the
proceſs with the remainder, I found a reſiduum of
one fourth of the whole. There ſeemed to be a
ſmall addition to the quantity of air after the firſt
part of the proceſs, but I could not perceive that
there was any after the ſecond. I reſumed the pro-
ceſs a third time, but did not find that I had made
more than one fourth of the whole immifcible with
At another time I heated the ſame kind of
iron in fixed air, till of three ounce meaſures and
three quarters of air there was a reſiduum of 0.8
of a meaſure, which was ſlightly inflammable, burn-
ing with a blue flame;; and in this caſe there was no
ſenſible addition to the quantity of air at all. Laſt-
ly, I heated iron in three ounce meaſures of fixed air
till there was an addition of 0.4 of a meaſure to the
quantity
'water.
1
Sect. II)
119
OBSERVATIONS ON FIXED AIR.
quantity of it; but there was a reſiduum of one
meaſure and a half not abſorbed by water, which
burned with a ſlightly exploſive blue flame.
SECTION III.
Miſcellaneous Obſervations on the Properties of fixed Air.
1. The Acidity of fixed Air.
Fix
IX ED air itſelf may be ſaid to be of the nature
of an acid, though of a week and peculiar ſort,
Mr. Bergman of Upfal, who honcured' me with a
letter upon the ſubject, calls it the aërial àcid, and,
among other experiments to prove it to be an acid,
he ſays that it changes the blue juice of tourneſole
into red. This Mr. Hey found to be true, and he
moreover diſcovered that when water tinged blue
with the juice of tourneſole, and then red with fixed
air, has been expoſed to the open air, it recovers its
blue colour again. Mr. Bewley proved in the moſt
deciſive manner, the acidity of fixed air, in the Ap-
pendix to the ſecond of my former volumes of Ex-
periments, p. 382.
14
2. Fixed
I20
OBSERVATIONS ON FIXED AIR. Part III,
1
2. Fixed Air expelled from Water by boiling,
The heat of boiling water will expel all the fixed
air, if a phial containing the impregnated water be
held in it; but it will often require above half an
hour to do it completely.
3. The freezing of Water impregnated with fixed Air.
Having ſucceeded in making artificial Pyrmont
water, I imagined that it might be poſſible to give
ice the ſame virtue, eſpecially as cold is known to
promote the abſorption of fixed air by water ; but
in this I found myſelf quite miſtaken. I put ſeve-
ral pieces of ice into a quantity of fixed air; con-
fined by quickſilver, but no part of the air was abi
forbed in two days and two nights ; but upon bring-
ing it into a place where the ice melted, the air was
abſorbed as uſual.
I then took a quantity of ſtrong artificial Pyrmont
water, and putting it into a thin glaſs phial, I ſet it
in a pot that was filled with ſnow and ſalt. This
mixture inſtantly freezing the water that was conti-
guous to the ſides of the glaſs, the air was dif-
charged plentifully, ſo that I catched a conſider-
able quantity, in a bladder tied to the mouth of the
phial
.
I alſo
Sett. IIT.
I 21
OBSERVATIONS ON FIXED AIR,
I alſo took two quantities of the fame Pyrmont
water, and placed one of them where it might freeze,
keeping the other in a cold place, but where it
would not freeze. This retained its acidulous taſte,
though the phial which contained it was not corked ;
whereas the other being brought into the ſame place,
where the ice melted very ſlowly, had at the ſame
time the taſte of common water only. That quan-
tity of water which had been frozen by the mixture
of ſnow and ſalt, was almoſt as much like ſnow as
ice, ſuch a quantity of air-bubbles were contained
in it, by which it was prodigiouſly increaſed in
bulk.
4. Fixed Air, how affeEted by Iron Filings and Sulphur.
I
Having obſerved. a; remarkable change in nitrous
air, by a mixture of iron filings and ſulphur, Į
wiſhed to know whether any alteration would be
made in the conſtitution of fixed air, by the ſame
means. I therefore put a mixture of this kind into
quantity of as pure fixed air as I could make, and
confined the whole , in quickſilver, left the water
ſhould abſorb it before the effects of the mixture
could take place. The conſequence was, that the
fixed air was diminiſhed, and the quickſilver roſe in
the veſſel, till about the fifth part was occupied by
it ; and, as near as I could judge, the proceſs went
on,
I
122
Part IIT:
OBSERVATIONS ON FIXED AIR::
on, in all reſpects, as if the air in the inſide had
been common air. :
What is moſt remarkable, in the reſult of this
experiment, is, that the fixed air, into which this
mixture had been put; and which had beeri in part
diminiſlied by it, was in part allo rendered-inſolu-
ble in water by this mears.' I made this experi-
ment four times, with the greateſt care, and ob-
ferved, that in two of them about one ſixth, and
in the other two about one fourteenth, of the origi-
nal quantity, was ſuch as could not be abſorbed by
water, but continued permanently elaſtic. Leſt i
ſhould have made any miſtake with reſpect to the
purity of the fixed air, the laſt time that I made the
experiment, I ſet part of the fixed air, which I
made uſe of, in a ſeparate veſſel, and found it to
be exceedingly pure, ſo as to be almoſt wholly ab-
forbed by water; whereas the other part, to which
I had put the mixture, was far from being fo.
Iron filings and brimſtone, I have obſerved, fer-
ment with great heat'in nitrous air, and I have ſince
obſerved that this proceſs is attended with greater
heat in fixed air than in common air.
5. Iron in fixed Air.
Though fixed air incorporated with water dif-
folves iron, fixed air without water has no ſuch
power,
1
Sect. III.
123
OBSERVATIONS ON FIXED AIR.
power, as I obſerved before. I imagined that, if it
could have diſſolved iron, the phlogiſton would have
united with the air, and have made it immiſcible
with water ; but after being confined in a phial full
of nails from the 15th of December to the 4th of
October following, neither the iron nor the air ap-
peared to have been affected by their mutual con-
tact
6. Fixed Air changed by Incorporation with Water.
Mr. Cavendiſh obſerved that a certain portion of
fixed air is no inore liable to be abſorbed by water
than common air. This, he ſtates at about one
ſixtieth
part
of the whole. I had the curioſity to
try, whether, if I ſaturated a quantity of water with
fixed air, and expelled it again by heat, that very
air which had actually been in the water, would not
be wholly imbibed by freſh water ; and whether I
could not, by this means, get a purer kind of fixed
air than that which is immediately procured by
means of chalk and oil of vitriol. This experiment
I made twice, with all the care that I could apply,
and found, in both the caſes, that even the fixed
air which had been in the water, contained as large
a portion of that which would not be imbibed by
water again, as the air which had been immediately
dinodged from chalk by oil of vitriol.
In
I 24
Part III,
OBSERVATIONS ON FIXED AIR.
In order to be more ſure of this fact, I was more
eſpecially careful, the ſecond time that I made the
experiment, to uſe every precaution that I could
think of, in order to prevent any error in the con-
cluſion. For this purpoſe, I took rain-water, and
boiled it about two hours, in order to get it perfectly
free from air; and I began to impregnate it with
fixed air a long time before it was cold, and there.
fore before it could have imbibed any common air ;
and, in order to expel the air from it, I put it into
a phial, which I plunged in a veſſel of water fet on
the fire to boil, taking care that both the phial con-
taining the impregnated water, and the glaſs-tube,
through which the air was to be tranfmitted, were
completely filled with the water, and no viſible
particle of common air lodged on the ſurface of it.
I alſo received the expelled air in water, which con-
tained very little air of any kind, leſt the very finall
degree of agitation which I made uſe of, in order to
make the water re-imbibe the air, ſhould diſengage
any air from it. Alſo, that leſs agitation, and leſs
time, might be ſufficient, I chiefly made uſe of lime-
water for this purpoſe. But notwithiſtanding all
theſe precautions, I found a very conſiderable reſi-
duum of air, not leſs than Mr. Cavendiſh had ſtated,
that water would not imbibe.
At a time when this reſiduuin of fixed air hardly
gave the leaſt ſenſible whiteneſs to lime-water, I
examined
2
Sect. III.
125
OBSERVATIONS ON FIXED AIR.
examined the ſtate of it, and found, by the teſt of
nitrous air, that it was very little worſe than com-
mon air'; two meaſures of this air, and one of ni-
trous air, occupying the ſpace of two meaſures
only.
7. Fixed Air expoſed to Heat.
I expoſed fixed air, as well as all the other kinds
of air, to a continued heat, and in this caſe I made
uſe of a green glaſs tube. I kept it in hot fand a
whole. day, ſo hot that one end of the tube was
much dilated, but had not burſt. Opening it under
water, one half of the tube was inſtantly filled, and
the remainder was the pureſt fixed air. I did not
perceive any thing depoſited on the glaſs, as in the
caſe of the marine and vitriolic acid air.
8. A Source of Deception from fixed Air, contained
in Water.
I obſerved that, in one produce of air from
a ſolution of biſmuth in the nitrous acid, I found a
ſmall quantity of fixed air, but that when I repeat-
ed the experiment, I could not find any appearance
of the kind. I afterwards made an obſervation
that will probably explain this diverſity of appear-
ances, and which alſo ſhews that, unleſs care be
maken
126
Part III:
OBSERVATIONS ON FIXED AIR.
"taken that the water in which the experiments are
made contain little or no fixed air, miſtakes of
this kind will certainly be made. For I found, at
one time that, if any kind of air was made to paſs
through a quantity of water containing much fixed
air, it would attract a portion of it, and would not
eaſily part with it afterwards.
At another time,
however (I think it was in colder weather) I found
that air conveyed through the ſame kind of water
(which was from a pump) did not attract any fixed
air. But I have not had leiſure to examine the cir-
cumſtances that might occafion this difference. Of
both the facts I am very certain.
9. Of fixed Air in acelous Fermentation.
As many of my obſervations related to the
vinous and putrefaćtive fermentations, I had the
curioſity to endeavour to aſcertain in what man-
ner the air would be affected by the acetous fermen-
tation. For this purpoſe I incloſed a phial full of
ſmall beer in a jar ſtanding in water ; and obſerved
that, during the firſt two or three days, there was
an increaſe of the air in the jar, but from that time
it gradually decreaſed, till at length there appeared
to be a diminution of about one tenth of the whole
quantity.
1
During
A
+
Sect. III.
127
OBSERVATIONS ON FIXED AIR.
1
During this time the whole ſurface of the liquor was
gradually covered with a ſcum, beautifully corrugated.
After this there was an increaſe of the air till there
was more than the original quantity ; but this muſt
have been fixed air, not incorporated with the reſt of
the maſs ; for, withdrawing the beer, which I
found to be four, after it had ſtood 18 or 20 days
under the jar, and paſſing the air ſeveral times
through cold water, the original quantity was dimi-
niſhed about one ninth. In the remainder a can-
dle would not burn, and a mouſe would have died
prefently.
The ſmell of this air was exceedingly pungent,
but different from that of the putrid effluvium.
10. Fixed Air from putrefying animal Subſtances.
1
When I made my experiments on air affected by
putrefaction, I obſerved that the water in which the
mice were ſuffered to putrefy, muſt have tranſ-
mitted ſome volatile effluvium from the putrefying
ſubſtances, into the ſurrounding air. This I ſup-
poſed muſt be phlogiſton, which putrefying ſub-
ſtances certainly do emit, loaded with that matter
which affects the noſtrils with the ſenſe of ſmell,
concerning which I know nothing. But beſides
this, I have found that, by this means, water be-
comes thoroughly impregnated with fixed air, dif-
charged, no doubt, from the putrefying ſubſtance.
That
128
Part III.
OBSERVATIONS 'ON FIXED AIR,
1
That this water might have got ſome fixed air I ſuf-
pected; but to find that it had
got
fo
very much,
I own ſurprized me.
Having put two dead mice into a quantity of wa-
ter, and exainining the proceſs after a month, I found
that the water was ſtrongly impregnated with a pu-
trid effluvium, which was very offenſive, and that
fome air, unabſorbed by the water, lodged in the top
of the phial ; it having been filledwith water, and in-
verted in a baſon of the fame. With the impreg-
nated water I filled a phial with a ground ſtopper
and tube, and making it boil, I expelled from it about
its bulk of 'air, which, when examined, was found
to be all pure fixed air. N. B. The water was very
turbid, and during the proceſs it depoſited a white
matter, reſembling a ſoft mucilage, with ſome ſmall
ſpecks of black in it.
1
<
ART
1
7
A
Se&. 1.
129
OBSERVATIONS ON FIXED AIR.
PA RT
IV.
OF THE CONSTITUENT PRINCIPLES OF FIXED AIR.
SECTION I.
Fixed Air contains Water.
HAT water is an eſſential ingredient in the
conſtitution of fixed air, as well as probably
of all kinds of air, is demonſtrated by my experiments
on terrà penderofa merata; and thefe may ferve to ex-
plain ſome of the following more early obſervations
on getting ſo little air from chalk.
Heat, I obſerved, fometimes is able to expel but
very little air from chalk. I kept a very ſmall
quantity of chalk in the focus of a burning lens,
twelve inches in diameter, and twenty inches focal
diſtance, more than half an hour, when the ſun was
near its greateſt altitude, on the 23d of July; but
notwithſtanding this long expoſure to fo intenſe a
degree of heat, it ſeemed to give as much fixed
air when thrown into a veſſel of water, acidulated
with oil of vitriol, as an equal quantity of chalk
which had not been expoſed to any heat at all. Of
Vol. I.
K
this
+
130
Part IV.
OBSERVATIONS ON FIXED AIR.
1
this, however, I only judged by the viſible effervef-
cence, and did not make any attempt to meaſure
the produce of air, in order to aſcertain the effect
of theſe different circumſtances with accuracy. .
I
have alſo kept chalk more than a quarter of an hour
in the ſtrongeſt heat of a ſmith's forge, in a crucible,
without making any ſenſible alteration in it.
When I put a quantity of chalk into a tall glaſs-
veſſel, and kept it in as ſtrong a ſand-heat as it would
bear, without melting, I extracted from it only
about its own bulk of air; and this was fixed air.
Terra ponderoſa aerata (a ſubſtance of which Dr.
WITHERING has given us an excellent analyſis)
gives no fixed air by mere heat. But I finid, that
when ſteam is ſent over it, in a red heat, in an
earthen tube, fixed air is produced with the greateſt
rapidity, and in the ſame quantity as when it is dif-
folved in ſpirit of falt: and, making the experiment
with the greateſt care, I find, that fixed air conſiſts
of about half its weight of water.
From two ounces of the terra ponderoſa I got,
by means of ſteam, 190 ounce meaſures of fixed air,
fo
pure that at firſt 150 ounce meafures of it were
reduced by agitation in water to three and a half,
and of the laſt produce, 30 ounce meaſures were
reduced to one. Examining the reſiduum of the
firſt portion by means of nitrous air, I found it to
..be of the ſtandard of 1.5.
After
+
Seå: i.* OBSERVATIONS ON FIXED AIR:
131
After this, attending to the water expended in
the proceſs, I found that I procured 330 ounice mea-
ſures of fixed air with the loſs of 160 grains of wa-
ter. According to this, as the air weighed 294
grains, the water in the fixed air muſt have been 80
parts of 147 of the whole.
In another experiment, having previouſly found
that three ounces of the terra ponderoſa yielded about
250 ounce meaſures of fixed air, I attended only to
the loſs of water in proćuring it, and I found it to
be about orie fifth' of an ounce, in two ſucceſſive
trials. The quantity of fixed air would weigh 225
grains, and the water expended about 100 grains;
ſo that, in this experiment alſo, the fixed air muſt
have contained about one half of its weight of
water.
That water enters into the compoſition of fixed
air, and adds conſiderably to its weigh, is farther
probable from the ſolution of terra ponderoſa in
ſpirit of ſalt. Becauſe when the ſolution is evapo-
rated to dryneſs, and the reſiduum expoſed to a red
heat; the weight of the air, and of this reſiduum,
exceeds that of the ſubſtance from which it was pro-
çured; and it is probable, that a red heat would
expel any marine acid adhering to it:
Forty eight grains of terra ponderoſa diſſolved in
fpirit of ſalt, and then evaporated to dryneſs, and
expoſed
K 2.
*32
OBSERVATIONS ON FIXED AIR, Part IV:.
expoſed to a red heat; loſt four grains, and yielded
eight ounce meaſures of fixed air, which would
weigh 7.2 grains; conſequently, three ſevenths of
the weight of the air was ſomething that had been
gained in the proceſs, and therefore probably water.
The near coincidence of the reſults of thefe dif-
ferent experiments is remarkable, and makes it al-
moſt certain, that no marine'acid is retained in the
terra ponderoſa that has been diſſolved in it, after
expoſure to a red heat; that the generation of the
fixed air carries off part of the water in the menftru-
um, and that this part of the weight is about one
half of the whole.
SEC,
Sext. II.
133
OBSERVATIONS ON FIXED AIR.
SECTION II.
Fixed Air may be procured by Means of nitrous Acid.
TH
HAT nitrous acid, and fixed air, conſiſt of
the ſame elements, differently combined, will
be demonſtrated by my experiments on the ſub-
ject of nitrous acid, and this may throw fome
light on the following more early experiments.
When heat can expel no more fixed air from
charcoal, it ſhould ſeem that ſpirit of nitre (if this
acid itſelf be not converted into fixed air) can ex-
tract more from it. For when I diſſolved, in ſpirit
of nitre, ſome pieces of charcoal, which had been
made with the ſtrongeſt heat of a ſmith's fire, long
continued, ſo that no more air could be expelled
from them by that means ; part of it was evidently
fixed air, as appeared by its precipitating lime in
lime-water.
One of the moſt deciſive experiments of this kind,
was made with ſpirit of wine, which nobody, I
believe, ſuſpects to contain any fixed air. For
though it makes lime-water turbid, Dr. Black has
juſtly obſerved, that this is produced by its union
with the water, in conſequence of which the lime
K 3
is
134
Part IV".
OBSERVATIONS ON FIXED AIR.
is precipitated in a cauſtic ſtate. A doubt, how-
ever, might be made, whether the turbid appear-
ance made by the air which I produced from the
ſpirit of wine, was really the effect of fixed air.
I endeavoured, therefore, and with ſucceſs, to pur-
ſue the experiment farther, and I did it in the fol.
lowing manner :
From a mixture of ſpirit of wine and ſpirit of
nitre, diluted with water, I produced a very con-
fiderable quantity of air, the greateſt part of which,
being received in a large body of lime-water, was
readily abſorbed, making the water very turbid.
Waiting about a quarter of an hour, till the preci-
pitated matter ſubſided, I poured the water from
it, and putting a very ſmall quantity of the preci-
pitate into ſome water out of which the air had been
well boiled, I poured a little diluted oil of vitriol upon
it, in a phial with a ground ſtopper and tube, and
found it to yield air in great plenty; and this air,
being admitted to lime-water, appeared to be, in all
reſpects, genuine and pure fixed air.
By this experiment it appears, that the ſubſtance
formed by the union of this air and the lime was
really chalk, or lime-ſtone, yielding genuine fixed
air with acids, exactly as other calcareous ſubſtances
do. The air was firſt generated from ſpirit of ni-
tre, and ſome other principle contained in the ſpi-
rit of wine : it was then incorporated with lime,
and
A
S&E7. II.
135
OBSERVATIONS ON FIXED AIR.
and after that diſlodged from the lime by the vitri-
olic acid, and made to appear in the form of air
again.
Fixed air was alſo generated in the ſolution of
iron in ſpirit of nitre.
Having diſſolved a quantity of iron in ſpirit of
hitre, diluted with an equal quantity of water, be-
fore the efferveſcence was over I removed the vef-
ſel in which it was contained (which was a tall glaſs
phial) into a fand-heat, and received the air, which
was tranſmitted through a glaſs tube, luted with a
mixture of ſand and clay, in phials containing rain
The quantity of air produced in theſe
circumſtances was very conſiderable, and part of
it was unqueſtionably fixed air, and what is re-
markably, to the purpoſe of the experiment, the
proportion of fixed air kept increaſing as the pro-
ceſs advanced, till at the laſt it was more than one
third of the whole. All the reſt of the air was
nitrous, and after the proceſs ſome of the iron
was found undiffolved.
water.
I
KA
SEC.
f
+
136
Part IV
OBSERVATIONS ON FIXED AIR.
SECTION
III.
Fixed Air may be formed by Means of fomething im-
bibed froin the Atmoſphere.
IT
T is evident, that the ſolutions of ſome of the
inetals in the nitrous acid, which do not imme-
diately yield any fixed air, will do ſo after they
have been expoſed to the cominon atmoſphere.
This appears in the following experiment:
Upon 108 grains of quickſilver I poured the
fame weight of ſtrong ſpirit of nitre, hanging
balanced in a pair of ſcales; when I obſerved that
the mixture loft weight by the eſcape of air, till it
was reduced to 123 grains. After this it gained
weight, till it was conſiderably more than the ori-
ginal quantity, but how much this additional weight
was I neglected to take any account of. The
mixture was made on the 25th of September, and
when it had ſtood in an open and ſhallow veſſel
till the 12th of January following, I diſtilled the
whole of it to dryneſs, in a glaſs phial; when I
found that one ſeventh of the air produced from
it was fixed air, and the reſt dephlogiſticated. !
took in all, ſeven ounce mçaſures, but loſt a good
deal
ز
Seet. III.
137
OBSERVATIONS ON FIXED AIR.
1
deal that eſcaped by the luting, and by the veſſel
breaking before the proceſs was over.
I then put the ſame quantity of quickſilver and
ſpirit of nitre into a clean phial, and diſtilling it to
dryneſs immediately, without giving it any oppor-
tunity of communicating with the external air (but
not beginning the diſtillation till the ſolution was
completed) I received in all thirty two ounce mea-
ſures of air, of which the firſt fourteen were pure
nitrous air, and the remainder pure dephlogiſticated
air, without the leaſt mixture of fixed air in either
of them.
Wood-aſhes have alſo the property of imbibing
one of the elements of fixed air from the cominon
atmoſphere, but they require conſiderable time to
do this, in any very ſenſible degree; for when
they had been well burned, I have not found that
they yielded any air that I could collect after being
expoſed to the open air a day or two; but that
they do become faturated with fixed air in a courſe
of time, is evident from the following experi-
ment.
From about three quarters of an ounce meaſure
of wood-afhes, from which I had, about three
months before, expelled as much air as I poſlibly
could, by the greateſt heat of a common fire, urged
with a pair of bellows, in a gun-barrel of about
half an inch diameter, I got by the ſame proceſs
fifteen
138 OBSERVATIONS ON FIXED ÅIR. Part IV,
fifteen ounce meaſures of air, eleven of which were
completely abſorbed by water, and the remain-
der burned with a lambent blue flame. The phlo-
giſton requiſite for this appearance might come
either from the gun-barrel, or from ſome imper-
ceptible bits of charcoal contained in the aſhes.
From twice the quantity of wood-aſhes, which
had been burned about the ſame time with the
others, in a much wider gun-barrel, I got aboup
twice the quantity of air, the greateſt part of which,
as in the former experiment, was fixed air, and
the remainder burned with a lambent blue flame,
Having taken this air in ſeveral portions, I ob-
ferved that the firſt contained a much greater pro-
portion of fixed air than the laſt, though what there
was of it ſeemed to be equally inflammable.
A more deciſive experiment relating to the gene-
ration of fixed air than that which is mentioned
above with wood-ajes, is one that I made with the
albes of pit-coal. Pit-coal itſelf, diſtilled in a glaſs
veſſel, yields no fixed air, but only inflammable
air, which, being fired in a wide-mouthed jar, burns
with a bright lambent Aame, without exploſion.
But the aſhes of the ſame pit-coal yielded much
air, of which one half was fixed, and the reſt in-
filammable. When I had expelled all the air that
I could from a quantity of theſe aſhes, I mixed
ſpirit of nitre with them, and they immediately
yielded
SeEt, III.
139
OBSERVATIONS ON FIXED AIR.
yielded as much air as before ; and of this one
half was fixed, and the reſt nitrous. Mixing more
ſpirit of nitre with the ſame aſhes again, the pro-
duce was the ſame as before.
To be more fully ſatisfied with reſpect to the
above-mentioned experiment with wood-alhes, and
alſo the quantity of fixed air imbibed by them in
a given time, I kept the ſame aſhes, and extracted
air from them at certain intervals. I alſo did the
fame thing with ſeveral other ſubſtances of a ſimilar
nature, and the reſults were as follows.
On the 18th of April, 1778, I extracted all the
air I could from half an ounce of wood aſhes, and
got about eighty ounce meaſures, half fixed air, and
half inflammable throughout; and on the 25th of
the ſame month I repeated the proceſs on the ſame
aſhes, in a gun-barrel, and got from them twenty
ounce · meaſures of air, the greateſt part of which
was fixed air, and the reſt inflammable. The
alhes were become almoſt black after the experiment.
June the 2d, I extracted, by heat, in a gun-
barrel, from wood aſhes from which air had often
been extracted before, in the ſame manner, and
the laſt time on the gth of May preceding, all the
air that they would yield. It was twenty one
ounce meaſures; the firſt portions of which were
half fixed air, and afterwards one third; the re-
mainder
+
!
1
140
Pärt IV.
OBSERVATIONS ON FIXED AIR.
A
mainder in both caſes being inflammable, probably
from the iron. A good deal of moiſture diſtilled
from theſe aſhes, though they ſeemed to be per-
fectly dry. After the proceſs, they weighed eigh-
teen penny-weights, and, judging from their colour,
not much more than two thirds of them had been
affected by the heat.
On the 23d of October following, the ſame wood
aſhes weighed nineteen penny-weights twelve grains,
and I got from them, in a gun-barrel, about thirty
ounce meaſures of air, of which more than twenty
five ounce meaſures was pure fixed air, the remain-
der infiammable, burning with a blue flame. They
had not all been equally affected by the heat. Af-
ter the proceſs, they weighed eighteen penny-weights
ſix grains. That they had attracted fixed air is
evident, eſpecially from the laſt proceſs, in which
the greateſt part of it was very pure.
On the 18th of April, 1778, I got, from an
ounce of pit-coal aſhes, in a gun-barrel, nineteen
ounce meaſures of air, of which at firſt two thirds,
and at the laſt one third was fixed air, and the
reſt inflammable. On the 24th of the ſame month,
I extracted from the ſame pit-coal aſhes (which,
as well as the wood aſhes in the preceding experi-
inent, had been expoſed to the open air in a diſh,
ſo as to lay about half an inch thick) 110 ounce
meaſures
**
1
1
Sect. III.
141
OBSERVATIONS ON FIXED AIR,
1
meaſures of air; but with more heat than before.
Of the firſt part of this air one third was fixed air,
but of the laſt hardly any, the remainder being in-
flammable, burning with a blue Aame; but fo
faintly, that probably the greateſt part of it was
phlogiſticated air.
Heating the ſame aſhes over again, in a ſhallow
iron veſſel, and letting them cool, I got from them,
by the ſame proceſs, fifteen ounce meaſures of air,
one third of which was fixed air, and the reſt in-
fainmable.
Common pit-coal, I have obſerved, yields no
fixed air, though the afbes do; but I have found
that one ſpecies of pit-coal, called Bovey coal, yields
fixed air in the firſt inſtance, which ſeems to indi-
cate that there is ſomething of a vegetable nature
in that coal. From half an ounce of this coal I
got, in a gun-barrel, about an hundred ounce mea-
fures of air, three fourths of which was fixed air
throughout, and the remainder infiammable; the
firſt part of it burning with a bright white Alame,
like inflammable air from common pit-coal, the
laſt part exploding like infammable air from
metals, only more faintly. Part of this air had
probably come from the gun-barrel.
Bone alhes, I found, had not the ſame pro-
perty of drawing fixed air froin the atmoſphere
that
.
142
Part IV:
OBSERVATIONS ON FIXED AIR.
that the aſhes of vegetable and minerable ſubſtances
have; but that the addition of ſpirit of nitre gives
them that property.
>
SECTION
IV.
Of the Generation of fixed Air from the vitriolic Acid.
I
Had an evident proof of the generation of fixed
air from the vitriolic acid united with ſpirit of
wine, or with ether, which is produced from them
both; ſo that theſe two acids, viz. the vitriolic and
nitrous, agree in being capable of forming both
depħlogiſticated and fixed air.
After going through the proceſs for making
ether, from concentrated oil of vitriol and rectified
ſpirit of wine, I had the curioſity to puſh the pro-
ceſs as far as it would go, in order to examine
whether any kind of air would be yielded in any
ſtage of it. I therefore continued the diſtillation
till the whole reſiduum was converted into a black
maſs, full of groſs matter; and taking as much
of the black lumps as filled about one fifth of añ
ounce
1
Sect. IV.
143
OBSERVATIONS ON FIXED AIR:
1
ounce meaſure, I put them into a tall glaſs veſſel,
and diſtilled them to dryneſs in a red hot fand heat.
The firſt air that came over was the common
air a little phlogiſticated, then the vapour of the
watery part, and after that a large quantity of air,
at firſt clear, but towards the middle of the pro-
ceſs
very turbid and white, but clear again at the
laſt. I received in all about a pint and a half, in
four portions, each of which contained about four
fifths of fixed air, and the reſt inflammable, burn-
ing with a blue flame; but the proportion of fixed
air was ſomething greater in the middle portions
than either in the firſt or the laſt
I thought it
poſſible that the cork, with which, as well as
with clay and ſand, the glaſs tube was joined to
the glaſs veffel that contained the materials, might
fupply the infiammable air in part, as I perceived
it was corroded and become black. It may be
worth while to repeat this proceſs in a glaſs retort.
Having gone over this proceſs with ſpirit of
wine, I recollected the black matter that was pro-
duced when I got vitriolic acid air from vitriolic
acid and ether; and therefore determined to repeat
chat proceſs and carry it farther; to fee whether
I ſhould, in any part of it, get fixed air, as in the
preceding experiment with the ſpirit of wine.
: I therefore put one eighth part of vitriolic ether
to a quantity of freſh diſtilled oil of vitriol, and
in !
I
t
1
144
Part IV:
OBSERVATIONS'ON FIXED AIR.
from it.au
។
in a glaſs phial with a ground-ſtopper and tube,
and with the heat of a candle, I got
great quantity of air, part of which was vitriolic
acid air, which was abſorbed by the water. But I
obſerved, as the proceſs advanced, the part that
was not readily abſorbed by water kept increaſing,
till at length the greater part of the produce was
of this kind; and in the middle of the proceſs it
was very turbid. Examining this air it appeared
to be fixed air, making lime: water turbid, and
being readily abſorbed by water; but there was a
reſiduum of phlogiſticated air, about one ſixth of
the whole.
I then put the remaining materials, which were
about an ounce meaſure, : into a glaſs veſſel; and
with a ſand heat I collected much more air than
before, about two pints in all, the firſt part of
which was the pureſt fixed air I had ever ſeen,
having the ſmalleſt reſiduum.
T'he laſt portion
had more reſiduum, and this burned with a lam-
bent blue flame. But this inflammable matter
might poſſibly come from the cork with which
the veſſel was cloſed, as before; though I think
it not ſo probable. At laſt the proceſs was inter-
rupted by, an accident; but I concluded, from ſeve-
ral circumſtances, eſpecially from the time that
elapſed before the vapour ceaſed. to iſſue from the
orifice of the veſſel (which continued buried in the
hot
Seet. V.
145
OBSERVATIONS ON FIXED AIR
1
hot fand) that more than twice the quantity of air
might have been collected. The air had been
very cloudy before the laſt portion, which contained
the reſiduum of inflammable air.
From this experiment, eſpecially that with the
echer, in the glaſs phial and ground ſtopper, I
think it is pretty evident, that fixed air is a fatti-
tious ſubſtance, and that the vitriolic, as well as the
nitrous acid, may be converted into it.
SECTION
V.
Of the Compoſition of fixed Air from dephlogiſticated
Air, and Phlogiſton, by the Generation of it fron
heating together Subſtances containing each of them.
Have ſeveral times given it as my opinion,
I
that fixed air is a factitious ſubſtance, and a mo-
dification of the nitrous and vitriolic acids, my
former experiments greatly favouring that conclu-
ſion; but that it was compoſed of dephlogiſticated
air and phlogiſton, though maintained by my
friend Mr. Kirwan, I was far from being ſatisfied
with, till I was forced to conſent to his proof of it
VOL. I.
L
from
146
OBSERVATIONS ON FIXED AIR.
Part TV
from my own former experiments, and gave him
leave to mention it, as he has done in his late
excellent paper on ſalts. But I have lately had
two direct proofs of it by experiment.
The firſt experiment which ſeemed to prove that
fixed air may be compoſed of dephlogiſticated air
and phlogiſton, was made with charcoal and red
precipitate, the charcoal being made with ſo great
a degree of heat, that no fixed air could be ex-
pelled from it, not even when it was wholly dif-
perſed by the heat of the ſun in vacuo. This
experiment is certainly, however, not ſo concluſive
as the former; becauſe, ſince dry wood and im-
perfectly made charcoal yield fixed air, it may be
ſaid that all the elements of this kind of air were
contained in the moſt perfect charcoal. And
though this ſubſtance alone will not, even with the
affiſtance of water, give fixed air, it might be ſaid,
that this might be effected by its treatment with
other ſubſtances, without their imparting any thing
to it ; eſpecially as the inflammable air which is
procured from charcoal by means of water appears
to contain fixed air, when decompoſed with de-
phlogiſticated air, I think, however, that I have
proved that this fixed air is really a compoſition of
phlogiſton contained in charcoal, and of the de-
phlogiſticated air with which it was inflamed, the
charcoal contributing nothing to it beſide its phlo-
giſton.
1
Seti. V.
147
OBSERVATIONS ON FIXED AIR:
giſton. In this place I ſhall only recite the facts.
concerning the production of great quantities of
fixed air from perfect charcoal and red precipitate.
In order to expel all fixed air, I made a quan-
tity of perfect charcoal from dry oak; and while
it was hot I pounded it, and immediately.mixing
four meaſures of it with one of red precipitate;
and putting them into an earthen retort, I preſently
got, in no greater a degree of heat than was necef-
ſary to revive the mercury, a large quantity of
air, half of which was fixed air. Afterwards the
proportion of fixed air was leſs, and towards the
concluſion of the experiment there came no fixed
air at all. This reſiduum was a little better at the
firſt than at the laſt; when it was of the ſtandard
+
of 1.5.
As this air contained a greater portion of phlo-
giſticated air than the common air of the atmoſphere,
and no ſpirit of nitre, or any thing that could yield
ſpirit of nitre, was concerned in the experiment, it
ſhould ſeem that phlogiſticated air may be com-
poſed of phlogiſton and deplogiſticated air ; though
this compoſition, according to the very capital dif-
covery of Mr. Cavendiſh; may be reduced to ſpirit
of nitre, or rather become one element in the
compoſition of that acid.
: 'In another experiment I hit upon a better pro:
portion of the charcoal and red precipitate for
L 2
making
**
148
Part IV.
OBSERVATIONS ON FIXED AIR.
making pure fixed ait. For mixing one ounce
of red precipitate (which all chemiſts, I believe, are
agreed to be the ſame thing with precipitate per ſe)
and one ounce of perfect charcoal, freſh from the
retort in which it was made; and putting them
into a coated glaſs veffel, I procured from the
mixture, by heat, about thirty ounce meaſures of
air, the whole of which was the pureſt fixed air,
leaving only about one fortieth pars not abforbed
by water, and this not inflammable, but of the
ſtandard of 1.7, or almoſt perfectly phlogiſticated.
This experiment made me recollect thoſe which
I had formerly made with charcoal heated in nitrous-
acid, in which I had always procured a quantity
of fixed air. I therefore repeated the experiment
with ſome of the ſame charcoal which I had uſed
in the preceding experiment, on the goodneſs of
which I could depend; and I found that, when it
was heated in the acid, in a glaſs phial with a
ground ſtopper, it gave air, one fifth of which was
fixed air. At another time I got air in this pro-
ceſs, one half of which was fixed air. To the
forination of this air, I preſume, that the phlogiſton
from the charcoal and the dephlogiſticated air,
which is known to be produced by heating nitrous
acid, muſt have contributed.
Being then apprized of the objection that might
be made to the uſe of charcoal, as, notwithſtanding
thc
1
Sext, V.
149
OBSERVATIONS ON FIXED AIR.
the great heat with which it was made, containing
at leaſt the elements of fixed air, I made uſe of
iron, to which no ſuch objection could be made;
and mixing an ounce of the red precipitate with
an ounce of iron filings, and then heating them in
a coated glaſs retort, I got twenty ounce meaſures
of air, of which only one ſeventh remained unabſorbed
by water. The reſiduum was of the ſtandard of
1:52, but ſlightly inflammable.
Again, from half an ounce of red precipitate, and
half an ounce of iron filings, I got twenty ſix ounce
meaſures of air, of which the firſt part was pretty
pure fixed air ; but afterwards one tenth of it re-
mained unabſorbed by water. Then, increaſing
the proportion of iron, I mixed one ounce of red
precipitate with two ounces of iron filings, and got
about forty ounce meaſures of air, of the firſt
por:
tions of which only one twentieth was unabſorbed by
water, though towards the concluſion of the proceſs
this reſiduụm was greater. In this proceſs I got, in
the whole, thirty ſix ounce meaſures of pure fixed
air, completely abſorbed by water, beſides what
was abſorbed both in the firſt reception of the air
(which was in veſels containing water) and after-
wards in transferring this air into thoſe veſſels in
which the quantity of it was noted, the whole of
which I ſuppoſe might be about four ounce meaſures
more. Examining the firſt reſiduym of this pro-
fels
.
1
13
1
*
? 50
Part IV
OBSERVATIONS ON FIXED AIR.
ceſs by nitrous air, the ſtandard of it was 1.6, and
afterwards 1.7*
Having heard that it was objected to this expe-
riment, that iron contains a quantity of plumbago,
and that the fixed air which I procured might come
from that ingredient in it (though the quantity was
certainly much too great to be accounted for in that
way) I made uſe of other metals, to which no ſuch
objection could be made, viz. braſs and zinc, and
with the ſame reſult.
With two ounces of braſs duít I mixed one ounce
of red precipitate, and in a coated glaſs retort I got
from it a quantity of air, two thirds of which was
fixed air. The ſtandard of the reſiduum was 0.6; ;
ſo that there had been too great a proportion of the
* It appeared, in ſome of theſe experiments, that three ounce
meaſures of dephlogiſticated air go into the compoſition of two
ounce meaſures of fixed air. For one ounce of this red precipitate
gave fixty ounce meaſures of dephlogiſticated air; and when mixed
with two ounces of iron filings, it gave about forty ounce meaſures
of fixed air that were actually abſorbed by water, beſides a reſidu.
um that was inflammable. I had the ſame proportion when I uſed
half an ounce of each of the materials. But when I uſed one ounce
of each, I got only twenty ounce meaſures of fixed air, including
the reſiduum. At other times I had different proportions with dif-
ferent quantities of iron filings and charcoal.
It muſt be obſerved, however, that part of the fixed air is always
imbibed by the water in which it is firſt received. Otherwiſe, in
this experiment, the fixed air would have weighed no more than
the dephlogiſticated air in the compoſition of it, ſo that nothing
would be left for the infiammable air,
red
1
Seg. 7
15:I
OBSERVATIONS ON FIXED AIR,
4
red precipitate. But fixed air was produced in a
quantity abundantly ſufficient for my purpoſe.
In a coated glaſs retort, I put a mixture of one
ounce of red precipitate and one ounce of. filings of
zinc, and got ſome air, part of which was clearly
fixed air; but the retort very ſoon cracking, put an
end to the experiment, and I did not think it necef-
ſary to repeat it. I imagine, however, that it will
only be at the beginning of this proceſs that much
fixed air can be procured, unleſs more precaution
be uſed in conducting it. For the neck of the re-
tort breaking quite off, there iſſued from it a ſtrong
-flame, which evidently aroſe from the burning of
the zinc in the dephlogiſticated air from the preci-
pitate.
As turbeth mineral gives dephlogiſticated air, as
well as red precipitate, I mixed this ſubſtance with
iron filings, ' and had a ſimilar reſult, when I heated
them together in an earthen retort. One ounce of
the turbeth mineral with two ounces of iron filings,
yielded about ſixteen ounce meaſures of air, of
.which about one third was fixed air, and the reſt of
the ſtandard of 1.5.
Another experiment which ſeems to prove the
formation of fixed air from phlogiſtion and dephlo-
giſticated air, is the expulſion of it from tliar bläck
powder which is formed by the union of lead and
mercury. This powder, I have obſerved; can orily
I 4
be
152
Part IV.
OBSERVATIONS ON FIXED AIR.
1
1
be made in pure air, which is no doubt abſorbed by
the metals; and this being again expelled by heat,
together with the phlogiſton which had belonged to
the lead, is that, I preſume, which forms the fixed
air that is found in this proceſs.
When I began to make obſervations on this black
powder, I mentioned my having expelled ſome
fixed air from it. This was from ſuch powder as
I had found ready made ; and therefore, not know-
ing with certainty what the compoſition of it was,
I diffolved one ounce of lead in pure mercury, and
then expelled it again in the form of this black pow-
der, which, when the running mercury was pretty
carefully preſſed out of it, weighed about twelve
ounces. Then expoſing it to heat, in a coated glaſs
retort, :I got from it about twenty ounce meaſures
of air, making allowance for the quantity of fixed
air, which, as I ſuppoſed, might have been abſorb-
cd by the water, in receiving and transferring the air
before any account was taken of the quantity of it.
Of this air about one thirtieth part only was not ab-
forbed by water. The reſiduum I did not examine.
I muſt however obſerve, that in general, beſides
the fixed air, I obtained a conſiderable quantity of
the pureſt dephlogiſticated air, from this black
powder.
In making the black powder that was uſed in the
preceding experiment, I occaſionally changed the
air
Seet. V. OBSERVATIONS ON FIXED AIR. 153
air in the phial, in which I ſhook the mercury, by
blowing into it, ſometimes with a pair of bellows,
and ſometimes with my mouth; and as it was ſug-
geſted that this might have fupplied the fixed air
which I afterwards found in the black powder, I
diffolved two ounces of lead in mercury, and got
the black powder without blowing into the veſſel at
all, only changing the air fo much oftner as was then
neceffary. From ſix ounces of the black powder
thus carefully prepared, I expelled four ounce mea-
fures and a half of air, of which one and a half was
pure
fixed air. This was ſufficient to ſatisfy me
that foine fixed air is certainly procured in this pro-
ceſs. The reſiduum of this fixed air was of the
ſtandard of 1.7, or 1.8. I did not at this time
ger from this powder all the air it would have
yielded.
Being now ſatisfied that there was no occaſion to
prepare this black powder with the precaution
mentioned above, I repeated the experiment with
ten ounces of it prepared in the readier method
which I had uſed before, with a view to examine
the reſiduum of the air, when the fixed air ſhould
be ſeparated from it. The produce of air was in
all about twenty three ounce meaſures, which I re-
ceived in four portions of five ounce meaſures each,
and another containing the remainder. All theſe
portions I examined ſeparately, obſerving the pro-
portion
1
I
1
154 OBSERVATIONS ON FIXED AIR. Part IV.
7
portion of reſiduum in each of them, and the qua-
lity, as meaſured by my uſual ſtandard, and the re-
ſult was as follows. Of the firſt portion there re-
mained one fourth, of the ſtandard of 1.6 į of the
ſecond one third, of the ſtandard of 1.44 ; of the
third one half, of the ſtandard of 0.8; and of the
fourth three fourths, of the ſame quality with the
preceding
In the laſt portion the refiduum was one half of
the whole, and that I found to be ſo pure, that,
mixing it with two equal quantities of nitrous air,
the ſtandard of it was 0.63; fo that the quality of
theſe reſiduums was continually purer, till at the
laſt it was pretty highly dephlogiſticated.
It
nay
be inferred from both theſe courſes of exs
periments, that fixed air conſiſts not of inflamma-
ble air (which I ſuppoſe neceſſarily contains water)
bup of pure phlogiſton, and dephlogiſticated air.
In the experiments with the red precipitate and iron,
no water at all is concerned, unleſs cither the iron
itſelf contain fome, or the mercury, or dephlogiſti-
cated air: ſince when the red precipitate is decom-
poſed by itſelf, nothing is produced beſides mercury
and dephlogiſticated air, without any water. The
experiment with the black powder will equally au-
thorize the ſame concluſion, as neither the lead, the
mercury, nor the pure air that combines with them,
has been ſuppoſed to contain any water. It muſt how-
I
ever
Seet. V.
155
OBSERVATIONS ON FIXED AIR.
L
ever be obſerved, that the greateſt part of dephlogiſ-
ticated air is water,
While I am upon the ſubject of this black pow-
der, I ſhall obferve, that it occurred to me to mix
with it more matter containing phlogiſton, in order
to ſee what change that would make in the reſiduum
of the produce of air.
From four ounces of the black powder mixed
with two ounces of iron filings; heated in an earthen
retort, I expelled fifty four ounce meaſures of air,
of which not more than four ounce meaſures were
fixed air, and the reſiduum, examined at different
times, was of the ſtandards of 1.3, and 1.44; but
the greater part of it was of 1.52, ſo that there was
a conſiderable production of inflamınable air from
the iron. In this experiment, I raiſed the heat
very gradually, till I had got one third of the pro-
duce of air. This I did from an idea that this mo-
derate heat might increaſe the quantity of the fixed
air, but it did not appear to make any difference in
this reſpect.
Then varying the proportion of the ingredients,
I mixed twenty ounces of the black powder with
only one ounce of iron filings, and receiving the
air in three portions, obſerved as follows. The
firſt portion, which contained ſix ounce meaſures,
had a reſiduum of
3.52
of the ſtandard of 1.6. The
ſecond, which was one ounce meaſure, had a reſi-
duum
4
156 OBSERVATIONS ON FIXED AIR; Part IV
duum of 0.12. of the ſtandard of 1.7; and the
third portion, which was only one ounce meaſure,
had a reſiduum of 0.12, of the ſtandard of 1.7.
Whether this was the whole of the produce of air, I
do not recollect.
In order to try more fully the effect of different
degrees of heat, I repeated the proceſs with the
black powder, only determining to ſuſpend the pro-
ceſs in the middle of the produce of air. Accord ,
ingly I heated two ounces of the black powder in a
porcelain veſfel; when I obſerved that fome por-
tions of the produce contained about one half fixed
air, and that this proportion kept growing leſs and
leſs, till the produce conſiſted of nothing but the
pureſt dephlogiſticated air, the ſtandard of it being,
with two equal meaſures of nitrous air, 0.2. I then
let the veſſel cool, and obſeryed that, on reſuming
the experiment, the air came with the ſame purity
to the laſt.
Examining the reſiduum in the retort, I found
half an ounce of red powder, the colour of which
could hardly be diſtinguiſhed from that of percipi-
tate per ſe. So that, no doubt, the mercury had
been converted into it, and this very pure air was
probably that which came from the precipitate as it
was reviving. In this way, therefore, it would be
eaſy to make this precipitate in large quantities,
could a method be found of ſeparating it from the
red
!
1
Seet. V.
157
OBSERVATIONS ON FIXED 'AIR.
red lead, with which it is, in this proceſs, neceffari-
ly mixed.
In the preceding experiment it will have been
obſerved, that, at firſt, the reſiduum was conſider-
ably phlogiſticated, but at the laſt remarkably pure.
An accident in a ſubſequent experiment I once
thought had diſcovered the cauſe of this difference.
In the middle of one of the proceſſes, in which I was
uſing the black powder only, heating it in a glaſs veffel,
a quantity of water was drawn up through the cube
that communicated with the recipient, and got into
the veſſel that contained the black powder; and in
all the remainder of that proceſs, the reſiduum of the
air was no better than about the ſtandard of 1.7.
Water came over along with this air to the very laſt,
though the bottom of the veſſel was red hot. When
the proceſs was over, the matter taken out of the
veſſel was ſtill moiſt, and of a dark grey colour.
On this I made a paſte of the powder with wa-
ter, and drying it a little, immediately repeated the
experiment with it; but I found no ſenſible differ-
ence between the ſubſtance in this ſtate, and that
which had not been wetted. Four ounces of it
yielded 120 ounce meaſures of air, of which about
twelve were pure fixed air, completely abſorbed
by water, and the reſt highly dephlogiſticated.
However, in one proceſs of this kind, from two
ounces and a half of this powder, which had been
moiſtened
+
1
1
158
Part IV.
OBSERVATIONS ON FIXED AIR.
moiſtened and dried again, I got ſeventy ounce
meaſures of air, of which only a very ſinall part
was fixed air, and the reſiduum was by no means
pure dephlogiſticated air.
For with two equal
meaſures of nitrous air, the ſtandard was 1.2 and
1.3. At other times alſo I have had much leſs
fixed air from this black powder when it had not
been wetted, than in ſeveral of the inſtances above-
mentioned; and I have not as yet been able to
difcover the circumſtance on which the produc-
tion of it in a greater or leſs quantity depends.
In the preceding proceſſes with this black pow-
der, I always got from it more or leſs of fixed
air: But thinking to produce more of it by heat-
ing this ſubſtance with a burning lens in dephlo-
giſticated air, I was ſurpriſed to find, that I only
increaſed the quantity of dephlogiſticated air in the
veſſel, and produced no fixed air at all. Whence
this remarkable difference could ariſe, I do not
pretend to ſay. It will be ſeen, that, in this pro-
ceſs with inflammable air, I found it to be a matter
of indifference whether I uſed this black powder
or the red precipitate; both of them equally im-
bibing inflammable air, without producing either
water or fixed air.
SEC.
1
Seat, :
159
OBSERVATIONS ON FIXED AIR.
1
:
SECTION
VI.
Of the Generation of fixed Air by heating Subſtances
containing Phlogiſton in dephlogiſticated Air.
A
NOTHER deciſive proof of the generation
of fixed air from phlogiſton and dephlogiſ-
ticated air, is the conſtant production of it when
iron is melted in dephlogiſticated air over mer-
cury, by means of a burning lens. This experi-
ment being a very pleaſing one, I repeated it very
often; and as it is on too ſmall a ſcale to admit
of great exactneſs, I ſhall mention the reſults of
feveral of them, obſerving, in the firſt place, that
no water is produced in this proceſs.
In fix ounce meaſures and a half of dephlogiſti-
Cated air, I melted turnings of malleable iron till
there remained only an ounce meaſure and one
third, and of this twenty ſeven thirtieths of an ounce
meaſure was fixed air. In ſix ounce meaſures of
.
dephlogiſticated air, of the ſtandard of 0.2, I melted
iron till it was reduced to two thirds of an ounce
meaſure, of which one half was fixed air, and the
remainder completely phlogiſticated. Again, I
melted
160
Part IV.
OBSERVATIONS ON FIXED AIR.
melted iron in ſeven ounce ineaſures and a half
of dephlogiſticated air of the fame purity with that
in the laſt experiment, when it was reduced to an
ounce meaſure and one third, and of this four
fifths was fixed air, and the remainder phlogiſti-
cated. In this caſe I carefully weighed the finery
cinder that was formed in the proceſs, and found
it to be nine grains; ſo that the iron that had been
melted (being about two thirds of this weight) had
been about ſix grains. I repeated the experiment
with the ſame reſult.
When the dephlogiſticated air is more impure,
the quantity of fixed air will always be leſs in pro-
portion. Thus having melted iron in ſeven ounce
meaſures of dephlogiſticated air of the ſtandard of
0.65, it was reduced to 1.6 ounce meaſures, and
of this only one third of an ounce meaſure was
fixed air,
Prullian blue is generally ſaid to be a calx of
iron ſuperſaturated with phlogiſton, though of late
it has been ſaid by fome, that it has acquired fome-
thing that is of the nature of an acid. From my
experiments upon it with a burning lens in de-
phlogiſticated air, I ſhould infer that the former
hypotheſis is true, except that the ſubſtance con-
tains ſome fixed air, which is no doubt an acid.
For much of the dephlogiſticated air diſappears,
juſt as in the preceding ſimilar proceſs with iron.
I threw
1
1
SPET. VI.
161
OBSERVATIONS ON FIXED AIR.
1
1
I threw the focus of the burning lens upon
fifty three grains of Pruſſian blue, in a veſſel
of dephlogiſticated air of the ſtandard of 0.53,
till all the colour was diſcharged. Being then
weighed, it was twenty two grains. In this proceſs
ſeven ounce meaſures and a quarter of fixed air
had been produced, and what remained of the air
was of the ſtandard of 0.94. Heating the brown
powder to which the Pruſſian blue was reduced in
this experiment in inflammable air, it imbibed
eight ounce meaſures and a half of it, and became
of a black colour ; but it was neither attracted by
the magnet, nor was it ſoluble in oil of vitriol and
water, as I had expected it would have been.
Again I heated Pruſſian blue in dephlogiſticated
air of the ſtandard of 0.2, without producing any
ſenſible increaſe of its bulk, when I found three
ounce meaſures of it to be fixed air, and the re-
ſiduum tolerably pure, for, with two meaſures of
nitrous air, the ſtandard of it was 1.35. The
ſubſtance had loſt eleven grains, the greateſt part
of which was evidently water.
To determine what quantity of fixed air Pruſſian
blue would yield by mere heat, I put half an ounce
of it into an earthen tube, and got from it fifty
fix ounce meaſures of air, of which ſixteen ounce
meaſures were fixed air, in the proportion of one
third in the firſt portion, and one fourth in the
Vol. I.
M
laſt.
.
162
Part IV.
OBSERVATIONS ON FIXED AIR.
laſt. The remainder was inflammable. There
remained 140 grains of a black powder, with a
very little of it, probably the ſurface, brown.
Comparing theſe experiments, it will appear that
the fixed air procured by means of Pruſſian blue
and dephlogiſticated air, muſt have been formed by
phlogiſton from the Pruſſian blue and the dephlo-
giſticated air in the veſſel. For if 240 grains of
this ſubſtance yield ſixteen ounce meaſures of fixed
air, ten grains of it, which is more than was uſed
in this experiment, would have yielded 0.6 ounce
meaſures. Nor is it poſſible to account for the
diſappearing of ſo much dephlogiſticated air, but
upon the ſuppoſition of its being employed in form-
ing this fixed air.
In all the experiments with iron it cannot be
doubted but that the greater part of the dephlo-
giſticated air (viz. the water in it) incorporates
with the iron, converting it into a ſcale, or fineiry
cinder, being the very fame ſubſtance with that
which is produced by tranſmitting ſteam over iron
when it is red hot; but at the ſame time ſome
phlogiſton muſt be expelled from the iron, and unite
with the dephlogiſticated air in the veſſel, in order
to form the fixed air that is found in it; as in other
caſes it unites with water, and makes inflammable air.
Perhaps as deciſive a proof as any of the real
production of fixed air from phlogiſton and deplilo-
giſticated
1
Seet. VI.
163
OBSERVATIONS ON FIXED AIR.
1
giſticated air, may be drawn from the experiments
in which I always found a quantity of it when i
burned ſulphur in dephlogiſticated air. In one of
thoſe experiments to which I gave more particular
attention, fix ounce meaſures and in half of de-
phlogiſticated air were reduced to about two ounce
meaſures; and one fifth of this was fixed air.
Much vitriolic acid air had been produced in this
proceſs: For, before I admitted any water to it,
the ſix ounce meaſures and a half were only reduced
to fix. When both the vitriolic acid and the fixed
air were abſorbed by water, the remainder was very
pure dephlogiſticated air, the ſtandard of it be-
ing 0.3.
I had always concluded that no fixed air could
be produced by the decompoſition of inflammable
air, which had been procured by means of the
mineral acids, becauſe I had not been able to do
it with that which I had got by means of the vitriolic
acid; but I learned from Mr. Metherie, that this
is peculiar to the vitriolic acid; the remains of which,
diffuſed through the inflammable air procured by
it, he conjectures, may decompoſe the fixed air
actually produced in the proceſs. See his Treatiſe,
p. 110. For, as I have hinted before, when the
inflammable air is produced from iron, by ineans
of ſpirit of falt, there is a very perceivable quan-
tity of fixed air, when it is united with dephlogiſ-
M2
cicated
1
i
A
OBSERVATIONS ON FIXED AIR.
164
Part IV.
ticated air. When I. decompoſed theſe two kinds
of air in equal quantities, they were reduced to
about 0.5 of a meaſure, and of this not more than
about one fortieth part was fixed air. This ex-
periinent, ought, however, to be added to the
other proofs of fixed air being produced by the
union of the dephlogiſticated air and phlogiſton.
The laſt inſtance of the generation of fixed air
froin phlogiſton and dephlogiſticated air, which I
thall mention in this ſection, is of a much more
ſtriking nature than any that I have yet recited.
Having made what I call charcoal of copper, by
making vapour of ſpirit of wine paſs over copper
when it was red hot, I took a piece of it, and,
with no very particular view, heated it in different
kinds of air. Among others, I did this in com-
mon air, and not obſerving any increaſe or decreaſe
of the quantity of air, concluded, but too haſtily,
that no change was made in it. For when I re-
peated the experiment in dephlogiſticated air, the
charcoal burned very intenſely; and when a part
of it was conſumed (which, like common charcoal
in the ſame proceſs, was done without leaving any
ſenſible reſiduum) I found that no heat which I
could apply afterwards had any farther effect on
what was left of the charcoal. Concluding, there-
fore, that ſome change. muſt be made in the quality
of the air, I examined it, and found about nine
tenths
Sett. VI.
OBSERVATIONS ON FIXED AIR.
165
1
17
tenths of it to be the pureſt fixed air, and the re-
ſiduum was ſuch as would have been made by
ſeparating the abſolutely pure part of the dephlo-
giſticated air, and leaving all the impurities in what
remained
Having aſcertained this fact, I repeated the ex-
periment, weighing the piece of charcoal very
carefully before and after the proceſs, and then
found that, by the loſs of one grain of the char-
coal, I reduced four ounce meaſures of dephlo-
giſticated air till one ninth only reinained unab-
forbed by water ; and again, with the loſs of one
grain and an half of the charcoal, I reduced fix
meaſures and an half of dephlogiſticated air till
five ounce meaſures and a half were pure fixed air.
In this proceſs there was a diminution of the
bulk of the air after the experiment, as might be
expected from the change of the air into one of
a heavier kind by means of a ſubſtance, or prin-
ciple, that could not add much to the weight of
it; but I did not accurately meaſure this. In one
of the experiments 4.3 ounce meaſures of dephlo-
giſticated air were diminiſhed, I obſerved, about
one thirtieth part of the whole. But being in a
pretty
wide veſſel, fuch a meaſure cannot be ac-
curate enough for computation. In this caſe, when
the fixed air was ſeparated by water, there was a
refiduum of 0.75 of a meaſure of the ſtandard of
M3
1.0
166
Part IV:
OBSERVATIONS ON FIXED AIR.
1.0, whereas the dephlogiſticated air beſore the ex-
periment had been of the ſtandard of 0.2.
That dephlogiſticated air actually enters into
the compoſition of fixed air in this experiment,
is evident from the weight of the fixed air, which
far exceeds that of the charcoal, which is diſperſed
in the proceſs. For in this laſt experiment the
weight of the fixed air produced was 4.95 grains.
Conſequently, ſuppoſing the charcoal to be wholly
phlogiſton, as it is very nearly ſo, fixed air may
be ſaid to conſiſt of 3.45 párts of dephlogiſticated
air, and 1.5 phlogiſton. So that the dephlogiſti-
cated air is more than three times the proportion
of the phlogiſton in it.
I muſt not conclude this ſection without ob-
ſerving that, I never failed to produce fixed air, by
heating iron in vitriolic acid air. I repeated the
experiment many times, and always had this very
remarkable reſult. In this caſe the acidifying prin-
ciple, which is the chief ingredient in dephlogiſti-
cated air, muſt have been ſupplied by the acid in
the air.
In one of the experiments, four ounce meaſures
of the vitriolic acid air were reduced to 0.65 of an
ounce meaſure; and of this three parts and one half
of the whole was fixed air, abſorbed by. lime water,
and the remainder was ſlightly inflammable. In
another experiment I could
not perceive any thing
infiam.
{
!
Seat, VII: OBSERVATIONS ON FIXED AIR. 167
inflammable in the reſiduum. It appeared to be
only phlogiſticated air. But theſe reſiduums are
always ſmall, ſo that it is not eaſy to diſtinguish
weakly inflammable air from that which is phlo-
giſticated:
SECTION
VII.
Of the Production of fixed Air by heating Subſtances
containing depblogiſticated Air in inflammable Air.
1
A
S fixed is always produced when iron, or any
other ſubſtance containing phlogiſton is
heated in dephlogiſticated air; ſo when precipitate
per ſe, or any other ſubſtance containing dephlo-
giſticated air is heated in inflammable air, fixed air
never fails to be procured.
In ten ounce meaſures of inflammable air from
malleable iron I revived red precipitate till there
remained only 1.1 ounce meaſure of air, and of
this. 0.07 ounce, meaſures was fixed air, being com-
pletely abſorbed by water. The weight of this
ajr would be 0.063 gr. But, ſince 360 grains
M4
of
168
Part IV.
OBSERVATIONS ON FIXED-AIR,
of iron will yield 1954 ounce meaſures of inflam-
mable air, the iron employed in procuring all the
inflammable air that was uſed in this experiment,
viz. 8.9 ounce meaſures (without allowing for any
that went to the revivification of the mercury)
would be 8.1 grains; and ſince M. Bergman ſup-
poſes, that 100 grains of iron contains 0.12 grains
of plumbago, the quantity of it in this iron would
only be 0.01008 gr. which is not quite a fixth
part of the weight of the fixed air.
With ſome precipitate per ſe, ſent me by M.
Berthollet, I revived mercury till eight punce mea-
ſures and a half of inflammable air was reduced to
IWO.ounce meaſures and a half, and of this .0.04
oz. m. at leaſt, was fixed air. This is not quite
ſo much in proportion as in the preceding ex-
periment, but abundantly more than the weight
of the plumbago,
In eight ounce meaſures of inflammable air I
revived minium (which I found to have exactly the
fame effect in this proceſs as red precipitate, or
precipitate per fe) till it was reduced to 1.2 ounce
meaſures; and of this 0,028 oz. m. was fixed
air, which would exceed the weight of the
plumbago more than three times. In reviving
lead from maſſicot (which I prepared by expelling
the pure air from minium) I had no fixed air in
the reſiduum
In
:
:
Sect. VII. OBSERVATIONS ON FIXED AIR. 169
1
In ſeven ounce meaſures of inflammable air
from tin by ſpirit of falt, I revived red precipitate
till it was reduced to 1.1. ounce meaſure; and in
this the fixed air was ſomething more than in
proportion to that in the laſt experiment.
I do.not know that any objection can be made
to the inflammable air from tin, as this metal has
not been proved.to contain plumbago. I wiſhed,
however, to repeat this experiment with inflamma-
ble air from fulphur. But though, when ſteam is
ſent over melted fulphur, a ſmall quantity of in-
flammable air is procured; yet, as ſulphur cannot
part with much phlogiſton, except in proportion
as it imbibes pure air, to form oil of vitriol, I could
not in this manner eaſily procure enough for my
purpoſe.
In order to ſupply the ſulphur with pure air, I
mixed with it a quantity of turbith mineral; but
this made it yield vitriolic acid air, though in great
abundance, there not being, I imagine, water
enough to form inflammable air: for when iron
is diſſolved in concentrated acid of vitriol, vitriolic
acid air is produced; but in diluted vitriolic acid,
the produce is infiammable air. With a view to
ſupply theſe materials with water, I ſent ſteam
over them; but it did not combine with the air,
which was ſtill only vitriolic acid air.
Since,
:
170
'OBSERVATIONS ON FIXED AIR. Part IV.
Since, however, vitriolic acid air unqueſtionably
contains the ſame principle which forms the in-
fiammability of inflammable air, this experiment
proves that ſulphur is not that ſimple ſubſtance
which the antiphlogiſtians ſuppoſe it to be; but
that it contains phlogiſton. Had it been nothing
more than a ſubſtance which had a ſtrong affinity
to pure air, it would have united with the pure
air from the turbith mineral, and have made
vitriolic acid; but no vitriolic acid air would have
been produced
That vitriolic acid air contains the fame inflam-
mable principle with infiammable air is evident
from the quantity of vitriolic acid air which F
produced by reviving copper from blue vitriol
in inflainmable air. Mr. Kirwan alſo produced
this air from fulphur and red precipitate. See his
Treatiſe on Phlogiſton, p. 29.
When I uſed a ſmall quantity of ſulphur in pro-
portion to the turbith mineral, the firſt produce
was vitriolic acid air, and afterwards dephlogiſti-
cated air, from the turbith mineral alone, the effect
of the fulphur having been exhauſted.
According to the antiphlogiſtic theory, phoſphorus,
as well as fulphur, is a ſimple ſubſtance; and
when it is ignited imbibes pure air, and thereby
becomes the phoſphoric acid, without parting with
any thing. But I find, that after the accenſion of
it
Sest, VII.
171
OBSERVATIONS ON FIXED AIR.
it in dephlogiſticated air, there is a conſiderable
quantity of fixed air in the reſiduum ; and this fixed
air could only be formed by the union of the de-
phlogiſticated air in the veſſel with the phlogiſton
contained in the phoſphorus. Mr. Kirwan had a
ſimilar reſult from phoſphorus confined in atmo-
ſpheric air. As it is not pretended, that there is
any plumbago in phoſphorus, this experiment is
not liable to the objection that has been made to
thoſe in which inflammable air from iron was made
uſe of.
Comparing this experiment with that in which
iron is ignited in dephlogiſticated air, and thoſe
in which nitrous acid is produced by the accenſion
of dephlogiſticated and inflammable air, this gene-
ral concluſion may be drawn, viz. that when either
inflammable or dephlogiſticated air is extracted from
any ſubſtance in contact with the other kind of air,
ſo that one of them is made to unite with the
other in what may be called its nafcent ſtate, the
reſult will be fixed air; but that if both of them be
completely formed before their union, the reſult
will be nitrous acid.
It has been ſaid, that the fixed air produced in
both theſe experiments may come from the plumbago
in the iron from which the inflammable air is
obtained. But ſince we aſcertain the quantity of
plumbago contained in iron by what remains after
1
3
its
172
Part. IV.
OBSERVATIONS ON FIXED AIR.
1
+
its ſolution in acids, it is in the higheſt degree im-
probable, that whatever plumbago there may be in
iron, any part of it ſhould enter into the inflamma-
ble air procured from it. Beſides, according to
the antiphlogiſtic hypotheſis, all inflammable air
comes from water only.
In the courſe of theſe experiments I. diſcovered
more completely than before: the ſource of my
former miſtake,' in fuppofing that fixed air, was a
neceſſary part of the produce of red lead, and alſo
of manganeſe. Both theſe ſubſtances, I find, give
of themſelves only dephlogiſticated air, and that of
the pureſt kind; and all the fixed air they yielded
in my former experiments i muſt have come from
the gun-barrel I then made. uſe sof, which would
yield inflammable air, which, with dephlogiſticated
air, forms fixed air. For though the dephlogiſti-
cated air from red lead was ſo pure that, mixed
with two meaſures of nitrous air; the three mea-
ſures were reduced to five hundredth parts of a
meaſure, and the ſubſtance gave no fixed air at all
when it was heated in an earthen tube or retort;
yet by mixing iron filings with it, or with manga-
neſe, as I had formerly done with red precipitate,
I
got more or leſs fixed air at pleaſure, and ſome-
time no dephlogiſticated air at all.
I cannot conclude theſe obſervations without
taking notice, how very valuable an inſtrument in
philo-
6
Sect. VII.
173
OBSERVATIONS ON FIXED AIR,
+
of my
philoſophy is a good burning lens. This muſt
have been perceived in many
former experi-
ments, but more eſpecially in theſe. By no other
means can heat be given to ſubſtances in vacuo, or
in
any
other kind of air beſides atmoſpherical; and
without ſome 'method of doing this, no ſuch ex-
periments as theſe can poſſibly be made. I there-
fore congratulate all the lovers of ſcience on the
ſucceſsful attempt of Mr. Parker to execute ſo
capital an inſtrument as he has done of this kind.
Such ſpirited and generous exertions reflect honour
on himſelf, and on our country. It is only to be
wiſhed, that we could have lenſes of a ſmaller ſize
(viz. from twelve to eighteen inches diaineter)
made tolerably cheap, ſo that they might be in
more common uſe. All the preceding experiments
were made with one of twelve inches in diameter.
1
:
!
SEC
1
174
Part IV.
OBSERVATIONS ON FIXED AIR.
SECTION VIII.
Of Air ačting through a Bladder. .
A
S it deciſively follows from my experiments
on the action of different kinds of air through
a bladder, that fixed air conſiſts of dephlogiſticated
air and phlogiſton, I ſhall introduce them in this
place.
One of my former experiments which I was
leaſt able to account for, was the diminution of
nitrous air in a bladder ſwimming at liberty in a
trough of water; the conſequence of which had
always been, that in a few days the nitrous air was
diminiſhed about one fourth, and this was phlogiſ-
ticated air. Al the progreſs that I had then made
in the inveſtigation of this curious fact, was finding
that it depended, as I then thought, upon the blad-
der being kept alternately dry and moiſt; becauſe
when the bladder was kept covered with water,
it remained full, and the air within it was not
changed. This was alſo the caſe when the blad-
der was kept dry. But I did not conſider that
when the bladder was kept under water, there was
1
no
Sect. VIII.
175
OBSERVATIONS ON FIXED AIR.
1
no air in contact with it; and I did not then
ſuſpect that this change in the air depended on the
action of the nitrous air upon the external common
air through a moiſt bladder; though I had found
that coagulated blood has a power of acting upon
air, and is of courſe liable to be acted upon by
air, through any bladder.
At length, ſuſpecting that this might be the caſe,
I made the following experiment. · Taking a
bladder which contained twenty ounce meaſures
of nitrous air, and tying it very tight, I introduced
it into a glaſs jar, which contained forty ounce
meaſures of common air ; becauſe, in that propor-
tion, they would be able, if they had any mutual
action, to faturate one another. Wiſhing at the
ſame time, to obſerve the changes that might
gradually take place in each of the kinds of airy
I examined them both at different periods.
The proceſs was begun on the 18th of May,
and on the 21ſt I found that there were only thirty
four ounce meaſures of the common air, and eleven
of the nitrous, the bladder being quite ſound; ſo
that it was ſufficiently evident, that the two kinds
of air, had affected each other through the ſub-
ſtance of the bladder. On the 25th of the fainé
month there were thitty one ounce méaſures and
a half of the common air, and four and a half of
the nitrous; and examining the ſtate of both of
them,
176
OBSERVATIONS ON FIXED AIR.
Part IV.
3
។
1
them, I found the ſtandard of the common air to
be 1.8, which was a ſtate very near that of extreme
phlogiſtication; and that of the nitrous 1.7. That
is, equal meaſures of this and of common air, oc-
cupied the ſpace of 1.7 meaſures, which ſhews that
it had almoſt loſt its power of affecting common
air, or to expreſs myſelf perhaps more correctly,
there was but a ſmall proportion of nitrous air
in it.
On the 8th of June I examined them for the
laſt time, after having obſerved no farther change
for ſome days in the quantity of the common air
(as indicated by marks which I had made on the
outſide of the jar) and I found only twenty eight
ounce meaſures of the common air, of the ſaine
quality as when I had examined it before, viz. of
the ſtandard of 1.8, and only three ounce meaſures
of the nitrous air, and it did not affect common
air at all. Neither of them contained any por-
tion of fixed air, and both of them extinguiſhed
a candle.
Nothing now remained to my complete ſatisfac-
tion, with reſpect to my former obſervation of the
diminution of nitrous air, contained in a bladder.
But I.farther wiſhed to ſatisfy myſelf with reſpect
to the action of imflammable air, on either com-
mon or dephlogiſticated air, in the fame circum-
ſtances. Nitrous air affects pure air by ſimple
contact,
.
+
Se67. VIII.
177
OBSERVATIONS ON FIXED AIR.
1
contact, without ignition; whereas, inflamınable
air, I had obſerved, has very little effect upon pure
air when they are ſimply mixed together. I was,
therefore, ſurprized to find that inflammable air has
a very conſiderable action upon dephlogiſticated air
through a bladder, without any aſſiſtance from
heat; and moreover, that the union of theſe two
kinds of air, thus produced, forms fixed air. The
experiments which I made for this purpoſe, were
as follows.
Into a jar containing 123 ounce meaſures of
dephlogiſticated air, I introduced a bladder, con-
taining twenty three ounce meaſures of inflamma-
ble air; and after a few days, I obſerved that the
bladder in which it was contained was become a
little flaccid. After about three weeks, I examined
both the kinds of air, and found that the bladder
contained only two ounce meaſures, and that this
was no longer inflammable, but extinguiſhed a
candle, though it had in it a mixture of pure air.
The air within the jar then contained one twentieth
of its bulk of fixed air. The dephlogiſticated air
was diminiſhed ſeven ounce meaſures; and from
being of the ſtandard of 0.5, with two equal mea-
ſures of nitrous air, it was now become of 1.4.
The bladder had a night ſmell of putrefaction, but
it was perfectly air tight.
VOL. I.
N
It
178
OBSERVATIONS ON FIXED AIR.
Part IV.
It is obſervable, that in this experiment part of
the dephlogiſticated air had paſſed unchanged into
the bladder of infiammable air, whereas the inflam-
mable air which had paſſed through the bladder
into the dephlogiſticated air, had united to it, and
formed fixed air. The tranſmiſſion of the dephlo-
giſticated air through the bladder was much more
remarkable in the following experiment.
Having introduced a bladder filled with inflam-
mable air into a large jar of dephlogiſticated air,
the bladder, after two days only, had in it a great
mixture of dephlogiſticated air, and was as much
diſtended as when it was firſt put into the jar.
A quantity of it exploded exactly like a mixture of
one third dephlogiſticated, and two thirds inflam-
mable air. The bladder was perfectly found and
ſweet, and the dephlogiſticated air was not ſenſibly
altered.
.. Again, having introduced a bladder containing
ten ounce meaſures of inflammable air into a jar
containing one hundred ounce meaſures of dephlo-
giſticated air, of the ſtandard of 0.3, I found, about
a month afterwards, that the air in the jar was
diminiſhed to ninety ounce meaſures, and the in-
flammable air to five ounce meaſures and an half.
The quality of the air in the bladder and of that in
the jar was very nearly the ſame, though the blad-
der was perfectly ſound and ſweet. The air in
thc
:
Sect. VIII.
179
OBSERVATIONS ON FIXED AIR.
the bladder, with equal meaſures of nitrous air,
was of the ſtandard of 0.76, and that in the jar
of 0.74. Both of them alſo contained a ſmall por-
tion of fixed air. In this caſe, therefore, both the
kinds of air had not only been tranſmitted through
the bladder, but ſome decompoſition had alſo taken
place within it, as well as within the jar.
In another experiment of this kind, both the
bladder of inflammable air, and the jar of dephlo-
giſticated air, after ſome time, contained each of
thein a portion of fixed air, and likewiſe both the
kinds of air unaffected by each other. For both
of them exploded when they were examined fe-
parately.
It ſeems to follow from theſe experiments, that
fixed air is really formed when inflammable air of
charcoal, &c. is exploded together with dephlogiſ-
ticated air; and alſo that the greatneſs of the heat
prevents its formation, when inflamimable air from
metals is uſed. For though, in the exploſions with
the electric ſpark, no fixed air was produced from
the decompoſition of the pureſt inflammable air,
it was evidently fo with the fame kind of inflam-
mable air in theſe experiments with a bladder in
which no heat is uſed.
The formation of fixed air from phlogiſton and
dephlogiſticated air, is more evident from the great
quantity of it which is found when an animal fub-
N2
ſtance
180
Part IV.
OBSERVATIONS ON FIXED AIR.
1
ſtance pytrefies in dephlogiſticated air, compared
with the ſmall quantity that is procured by its
putrefying in inflammable air.
After the preceding experiments on the conſe-
quence of having one kind of air in the bladder,
and the other in the jar in which it was confined,
I filled the bladder with the ſame air that was in
the jar, and let them remain till they became
putrid and burſt. The jar and the bladder of des
phlogiſticated air contained together one hundred
ounce meaſures of the ſtandard of .95, but after
the proceſs and waſhing the air in water there
were only 37.5, qunce meaſures, which was phlo-
giſticated.
At another time ninety ounce meaſures of de-
phlogiſticated air of the ſtandard of 0.16, were
reduced to forty ſeven ounce meaſures of the ſtan-
dard of 0.6; whereas a jar of inflammable air of
the ſame ſize, and treated in the ſame manner,
contained, after the proceſs, not more than one
thirtieth of its bulk of fixed air. In this it was
obſervable, that the bladder and the air were moſt
abominably offenſive, whereas the bladder which
had been in dephlogiſticated air was hardly of-
fenſive at all.
It will appear by computation, that in both
theſe caſes of the formation of fixed air, by the
bladders putrefying in dephlogiſticated air, phlo-
giſticated
Sect. VIII. OBSERVATIONS ON FIXED AIR.
181
giſticated air was produced, six ounce meaſures
being generated in the former caſe, and five in the
latter; and though all fixed air contains a part
not abſorbed by water, and this is always more or
lefs phlogiſticated, this was much more than in
that proportion, the phlogiſticated air being in
the former caſe one ſixth of the whole, and in
the latter nearly one half. For in the former cafe
the phlogiſticated air before the proceſs was 31.7
ounce meaſures, and after it 37, and in the latter
it was 4.86 ounce meaſures before, and
9.4
after,
V
J
1
1
N3
BOOK
182
Part I.
OBSERVATIONS ON
1
I
Β Ο Ο Κ
II.
EXPERIMENTS AND OBSERVATIONS RE,
LATING TO INFLAMMABLE AIR.
PARTI.
EXPERIMENTS AND OBSERVATIONS RELATING TO
THE PRODUCTION OF INFLAMMABLE AIR,
SECTION I.
Of infiamnable Air from Metals, by means of
Acids, &c.
THE metals from which this ſpecies of air
has been procured are iron, zinc, and tin. I
found it in copper, and lead by ſpirit of falt, as may
be ſeen in the account of the diſcovery of marine
and air. I have alſo procured it in various other
ways; and have lately found that regulus of an-
timony diffolved in marine acid, with the appli-
cation
1
Sect. I.
183
INFLAMMABLE AIR.
cation of heat, yielded a ſmall quantity of air,
which was weakly inflammable. Biſmuth and nickel
were diffolved in marine acid with the help of a
conſiderable degree of heat, but little or no air
was got from either of them. If there was any
more than the common air which had lodged
within the phial containing the mixture, I could
not perceive that it was inflammable: but theſe
metals treated in this manner yielded a ſtrong ſinell
of liver of ſulphur.
It is ſomething remarkable, that all the acids
that produce any air by the ſolution of metals give
inflammable air, except fpirit of nitre only, which
forms a different kind of union with the inflam-
inable principle; making nitrous cir, more or leſs
modified. Beſides oil of vitriol and ſpirit of ſalt,
I have obſerved that the vegetable acid alſo pro-
duces inflammable air, by the ſolution of metals,
though in a much leſs quantity. Perhaps the
proportion of the ſtrength of the acids may be aſ-
certained by this means. The concentrated vinegar
which I made uſe of in my experiments on the
vegetable acid air, diſſolved zinc almoſt as rapidly
as ſpirit of falt, and produced inflammable air; and
radical vinegar, which is unqueſtionably a pure
vegetable acid, had the fame effect when applied
both to zinc and iron.
i
N4
In
184
Part 7
OBSERVATIONS ON:
1
In order to meaſure the ſtrength of this acid, I
put as much radical vinegar as occupied the ſpace
of fifty two grains of water upon a quantity of filings
of zinc diluted with water, and found that it yielded
one fourth of an ounce ineaſure of inflammable
air, without heat; and two ounce meaſures more
with heat; and a little more might have been
procured, if care had been taken that no part of
the liquor had boiled over. What proportion this
produce of inflammable air bears to a ſimilar pro-
duce from ſpirit of ſalt may be found by com-
paring this obſervation with ſome that are men-
tioned relating to marine acid air.
In my firſt experiments on fixed air, I found
that, when a mixture of iron filings and brimſtone,
moiſtened with water, was made to ferment in it,
a part of it was made immiſcible with water, that
is, that there was in it a greater reſiduum of phla-
giſticated air than uſual, which I ſuppoſed to come
from the phlogiſton ſet looſe in this proceſs; though
I could not find that phlogiſton in any other pro-
ceſs produced that effect. At that time it could
not but occur to me, that, poſſibly, this mixture
itſelf might generate air, in which caſe the fact I
have been reciting would not prove that there had
been any alteration in the conſtitution of the fixed
air ; ſince there would have been a real addition to
it, of another kind of air from the mixture. To
try
Se&. 1.
INFLAMMABLE AIR,
185
try this, I then made this mixture to ferment under
water, and found that no air whatever was produced
from it.
I have ſince tried the fame thing in the beſt
vacuum that I could make with Mr. Smeaton's air
pump; when, though the fermentation went on as
uſual, yet when water was admitted to it afterwards,
no air was found in the receiver. I alſo made
this fermentation when the materials were buried
in quickſilver, and in theſe circumſtances alſo no
air was produced in the temperature of the at-
moſphere.
I mention theſe circumſtances, becauſe I have
found that when this fermentation is made in quick-
ſilver, and in a warm place, a true inflammable air
is generated. The experiment was made in as
accurate a manner as I could contrive, and in the
courſe of it, it will be ſeen that probably a quantity
of vitriolic acid air was alſo generated, and ab-
forbed again by the water that was mixed with
the iron and brimſtone, and which is neceſſary to
enable them to act upon each other.
Having filled a ſmall phial with a mixture of
iron filings and brimſtone moiſtened with water,
I plunged it in a veſſel filled with quickſilver,
ſtanding inverted in a baſon of the ſame, and placed
the whole apparatus near the fire. In about half
an hour the fermentation began, and ſo much air
iſſued
1
1
+
186
Part I.
OBSERVATIONS ON
5
In a
iſſued from the mixture, as occupied the ſpace
of four times the bulk of the materials.
few minutes the quantity of air diminiſhed, being
probably vitriolic acid air, and having been ab-
forbed by the water; but there remained about
one fourth of the bulk of the mixture that was
permanent air, not imbibed by water; and this
was infammable.
Since zinc, as well as iron, yields inflammable air
with oil of vitriol, I ſuſpected that poſſibly it
might be affected as iron is by the oil of vitriol
ſer looſe from the ſulphur in this proceſs, and I
found that wlien I ſubſtituted filings of zinc 'for
the filings of iron, in the circumſtances above-
mentioned, they anſwered equally well. In this
experiment a quantity of air was produced equal
to the bulk of the materials, all ſtrongly inflam-
mable,
Having once put a por of iron filings and
brimſtone into a jar of nitrous air (the firſt effect
of which is to reduce it to one fourth of its bulk,
and leave it in the ſtate of phlogiſticated air) and
having ſome time after this found the air much
increaſed in quantity, and ſtrongly inflammable,
I had ſome doubt whether the inflammable mat-
ter came from fome farther change in the nitrous
air, or from an exhalation of proper inflammable
air from the iron and brinſtone. My doubt aroſe
from
5
Seet. I.
187
INFLAMMABLE AIR.
i
from my never having found that this paſte of iron
filings and brimſtone, whether kept in water, or
in vacuo, had yielded air at any time, except in a
conſiderable degree of heat. In conſequence, how-
ever, of repeated experiments, I am now fatisfied,
that the inflammable air came from this mixture.
For though ſome pots of it have not yielded in-
flammable air, they have all, with long keeping,
even in the temperature of the atmoſphere, yield-
ed either phlogiſticated or inflammable air ; ,the
latter generally when the compoſition was freſh
made, and the former when it was old.
Theſe experiments have alſo led me to the ob-
ſervation, that, in this and many other caſes of the
diminution of common air by phlogiſtic proceſſes,
a true inflammable air is firſt produced, and in its
naſcent ftate; as it may be called, is immediately
decompoſed, previous to the phlogiſtication of the
common air. The very ſame ſubſtances which,
in water or quickſilver, yield inflammable air, only
phlogiſticate common air: ſo that I am almoſt
ready to conclude univerſally, that air is never phlo-
giſticated, but by materials which, in certain cir-
cumſtances, would yield inflammable air; though
when inflammable air is previouſly produced, and
then mixed with common air, it will not be de-
compoſed in the temperature of the atmoſphere,
except in a very ſmall degree. Theſe two kinds
of
A
:
188
OBSERVATIONS ON
Part I.
of air will, therefore, continue mixed without much
affecting each other, except in a red heat, by
which the inflammable air is fired. It is then well
known to ceaſe to be inflammable air, the phlo-
gifton being ſeparated from it, and uniting with
the dephlogiſticated air in the common air ; when
nothing is left but the phlogiſticated part of the
common air, which is about three fourths of the
whole.. I have ſince obſerved that nitrous acid is
forined in theſe circumſtances.
The experiments which led to theſe concluſions,
and which I ſhall now proceed to recite, may ſerve
as a càution to myſelf and others, not to be too
haſty in drawing general concluſions; ſincé what
may appear to be the ſame inaterials, and the ſame
preparation of them, may have different reſults, in
conſequence of there having been ſome circum-
ſtance, reſpecting either the materials or the pro-
ceſs, that was unnoticed, but which was the ſecret
cauſe of the unexpected reſults.
That nitrous air might be changed into inflam-
mable air, was not extremely improbable a priori;
ſince I had found that it contained nearly as much
phlogiſton as inflammable air, bulk for bulk ; and
ſince it. is, by ſeveral proceſſes; convertible into
what has the appearance of a ſpecies of inflamma-
ble air. Beſides, in this very caſe, the ſame com-
poſition of iron filings and brimſtone, which I now
find
Sect. I.
INFLAMMABLE
189
AIR.
find generally yields inflammable air in the tempe-
rature of the atmoſphere, does not do ſo at all times.
Thinking that if the iron filings and brimſtone
had really yielded the inflammable air which I
found in the veſſel of nitrous air, it would do the
fame in common air, I confined a large pot of this
mixture in a very finall quantity of common air
in the beginning of February, 1779. But though
on the 19th of May following it was increaſed in
bulk, it was all mere phlogiſticated air, and had
nothing inflammable in it. Even the air that was
entangled within the cavities of this pot of iron
filings and brimſtone, and which I catched by
breaking it under water, was not inflammable. It
is poſſible, however, as I obſerved before, that
this phlogiſticated air might have been inflammable
air in its origin, or naſcent ſtate, and have become
phlogiſticated air afterwards. At another time I
put a pot of this mixture under water, as I had
done formerly, and now alſo obſerved, that though
it fermented very well, and turned black, yet ir
did not yield a particle of air in about a fort-
night: and in experiments of this kind few perſons,
I believe, would look for any farther change be-
yond that time.
Soon after, however, I found that a pot of this
mixture, freſh made, and kept under water three
weeks, had yielded about its bulk of air; and
this
190
Part 1
OBSERVATIONS ON
this was ſtrongly inflammable. But at the ſame
tiine another mixture of this kind, kept in the
fame circunſtances, yielded only phlogiſticated air ;
and yet I did not knowingly make any difference
in the compoſition, always mixing equal bulks of
the two ingredients.
As the phlogiſton which conſtituted the inflam-
mable air in the experiments that occaſioned theſe
muft probably have come from the iron, and not
from the fulphur; eſpecially ſince iron alone is
capable of making a very remarkable change in
nitrous air, I confined a quantity of this air, in a
veſſel full of iron nails, from the beginning of
February to the 18th of May; but after this long
interval it was only phlogiſticated air, and not in
the leaſt inflammable.
Having found, however, that this mixture of iron
filings and brimſtone was capable of producing in-
Hammable air in water, I made a trial of it in
quickſilver, and found it to have the ſame effect.
For confining a quantity of this mixture in quick-
ſilver from the 13th to the 30th of June, in the
temperature of the atmoſphere, it had yielded, in
this time, its own bulk of air, ſtrongly inflam-
mable.
I found afterwards, in a proper number of trials,
that in a ſufficient ſpace of time, this mixture in-
crcafed all the kinds of air into which I intro-
duced
1
Sest. 1
INFLAMMABLE AIR.
191
cluced it, by the addition of a quantity of inflam-
inable air, more or leſs, according to circunſtances,
known or unknown. But when the experiment
was inade in common air, it firſt diminiſhed it
about one fourth, as I have often noted; and ſome
time after that I perceived an addition made to
the bulk of the air, and examining it, found it at
firſt to be ſlightly inflammable, but afterwards more
ſtrongly fo. This experiment Shiews that; in the
firſt inſtance, the inflammable air yielded by iron
filings and brimſtone muſt have been decompoſed
by uniting with the dephlogiſticated air in the com-
mon air.
It appeared upon one occafion, recited above,
that one pot of this mixture, freſh mode, produced
inflammable air, at the ſame time that a pot of an
old mixture of this kind yielded only phlogiſticated
air. But at what time thoſe mixtures will ceaſe
to give infiammable air, and begin to yield phlo-
giſticated air, I cannot determine. For I find that
on the 234 of June a pot of iron filings and brim-
ſtone, which muſt have been mixed about a year
before, confined in a ſinall quantity of common
air, had made an addition to it of three ounce
meaſures on the 26th of July; and this air was
inflammable. At the fame time I found that
another quantity, which had been mixed the ift
of July, had yielded infiammable air, in about the
4
fame
192
Part 1.
OBSERVATIONS
ON
fame proportion, according to the time. Alſo
ſome old iron filings and brimſtone, which had
been taken out of the pot, and mixed with water
the 3d of July, had yielded about one tenth of its
bulk of air on the ad of Auguſt, ſtrongly inflam-
mable.
That future experimenters inay form ſome idea
of the quantity of inflammable air that they may
generally expect from ſuch mixtures as I have uſually
made of iron filings and brimſtone, uſing equal
bulks of each, and therefore be leſs apt to deceive
themſelves in the reſults, I ſhall recite the iſſue of
fome that I made with this and other mixtures,
and which I was obliged to put an end to when
I removed my habitation on the 21ſt of July,
1780.
A gallipot, containing an ounce meaſure and
half of this mixture, having been confined, in a
ſmall quantity of common air in the beginning of
July, 1779, had at the time above-mentioned
produced fourteen ounce meaſures of air, ſtrongly
inflammable; but the production was much more
rapid at the firſt than afterwards. The mixture
was very hard.
Another gallipot of the ſame ſize, put into a
veſſel of water, without any air, on the 23d of
June, 1779, had three ounce meaſures of inflam-
mable air taken from it on the 26th of July fol-
3
lowing,
1
Seet. 1
193
INFLAMMABLE
AIR.
lowing, and at this time there were eleven ounce
meaſures, ſtrongly inflammable. The mixture was
very ſoft.
1
Another equal quantity had yielded ſtrong in-
flammable air from the 24th of June to the 15th
of July, 1779, and had from that time yielded
about three ounce meaſures of air, but ſlightly
inflammable. The mixture was very ſoft.
There is the ſame uncertainty attending experi-
ments made with liver of ſulphur, which alſo ex-
hales phlogiſton, and produces the ſame effect both
on common air and nitrous air, as iron filings and
brimſtone. On the 19th of May, 1779, I found
a quantity of nitrous air, in which ſome liver of
fulphur had been confined from the 12th of Decem-
ber preceding, and which was conſiderably increaſed
in bulk, to be ſtrongly inflammable ; and yet an-
other quantity of this ſubſtance, and freſh made, was
confined in quickſilver ſeveral months without pro-
ducing any air at all.
I have procured inflammable air, in a conſider-
able quantity, by diffolving iron filings in a ſolution
of galls; and very probably the ſame would be
produced by means of any other aſtringent ſub-
ſtance. Indeed moſt things that really decompoſe
the metal, and do not unite with the whole maſs of
it, will, I imagine, ſet looſe the phlogiſton it con-
tains, in the form of inflammable air; though, in
Vol. I.
O
ſeveral
1
.
194
OBSERVATIONS ON Part I.
I
ſeveral of the caſes, the phlogiſton might join
ſome of the principles in the menſtruum, and con-
tribute to compoſe a different ſubſtance.
I was led to this obſervation of the production
of inflammable air by the ſolution of galls, in con-
ſequence of being informed by Mr. Delaval, that
ink might be made by putting iron to the folu-
tion of galls; for that the acid in the vitriol, which
is commonly uſed for the purpoſe of making ink,
is an unneceſſary, and frequently an inconvenient
ingredient.
Having mixed a quantity of pounded galls, iron
filings, and water, I firſt obſerved, that, after a day
or two, the whole maſs was very much ſwelled,
and that it was full of bubbles of air, which at the
ſurface were very large. Suſpecting, from the
ſmell, and other circumſtances, that the air con-
tained in them was inflammable, I burſt feveral of
them near the flame of a candle, and found that
they all made ſmall exploſions, ſo that I could have
no doubt concerning the quality of the air.
I then mixed three ounces of pounded galls
with water and iron filings, the quantity of which
I did not note; and covering them with a large
jar full of water, found that, in about a week, they
had produced fix ounce meaſures of air, which
was ſtrongly inflammable, exactly like that which
is produced from iron by the acids. In the ſame
3
manner
Seet. II.
195
INFLAMMABLE AIR.
1
manner I procured a quantity of this inflammable
air by putting the above-mentioned mixture into
a phial with a ground ſtopper and tube. But this
proceſs is too ſlow for any uſe.
SECTION II.
of inflammable Air from Oil.
TH
HE electric ſpark taken in any kind of oil
produces inflammable air, as I was led to
obſerve in the following manner. Having found,
as will be mentioned hereafter, that ether doubles
the quantity of any kind of air to which it is ad-
mitted ; and being at that time engaged in a courſe
of experiments to aſcertain the effect of the electric
matter on all the different kinds of air, I had the
curioſity to try what it would do with common air,
thus increaſed by means of ether. The
The very firſt
ſpark, I obſerved, increaſed the quantity of this
air very conſiderably, ſo that I had very foon fix
or eight times as much as I began with; and
whereas water imbibes all the ether that is put ta
any kind of air, and leaves it without any viſible
O2
change,
196
OBSERVATIONS ON
Part I.
change, with reſpect to quantity or quality, this:
air, on the contrary, was not imbibed by water. It
was alſo very little diminiſhed by the mixture of
nitrous air. From this it was evident, that it
had received an addition of ſome other kind of air,
of which it now principally conſiſted.
In order to determine whether this effect was
produced by the wire, or the cement by which the
air was confined (as I thought it poſſible that phlo-
giſton might be diſcharged from them) I made
the experiment in a glaſs ſyphon, and by that
means I contrived to make the electric ſpark
paſs from quickſilver through the air on which I
made the experiment, and the effect was the ſame
as before. At one time there happened to be a
bubble of common air, without any ether, in one
part of the fyphon, and another bubble with ether
in another part of it; and it was very amuſing to
obſerve how the fame electric ſparks diminiſhed
the former of theſe bubbles, and increaſed the
latter.
It being evident that the ether occaſioned the
difference that was obſervable in theſe two caſes,
I next proceeded to take the electric ſpark in a
quantity of ether only, without any air whatever;
and obſerved that every ſpark produced a ſmall
bubble; and though, while the ſparks were taken
in the ether itſelf, the generation of air was now,
yet
Seet. II.
197
INFLAMMABLE AIR.
yet when ſo much air was collected, that the ſparks
were obliged to paſs through it, in order to come
to the ether and the quickſilver on which it reſted,
the increaſe was exceedingly rapid ; ſo that, making
the experiment in ſmall tubes, as fig. 16, Pl. I. the
quickſilver ſoon receded beyond the ſtriking dif-
tance. This air, by paſſing through water, was dimi-
niſhed to about one third, and was inflammable.
One quantity of air produced in this manner
from ether I ſuffered to ſtand two days in water,
and after that I transferred it ſeveral times through
the water, from one veſſel to another, and ſtill.
found that it was very ſtrongly inflammable ; ſo
that I have no doubt of its being genuine inflam-
mable air, like that which is produced from metals
by acids, or by any other chemical proceſs.
Concluding that the inflammable matter in this
air came from the ether, as being of the claſs of
oils, I tried other kinds of oil, as oil of olives, oil
of turpentine, and eſſential oil of mint, taking the
electric ſpark in them, without any air to begin
with, and found that inflammable air was produced
in this manner from them all. The generation of
air from oil of turpentine was the quickeſt, and
from the oil of olives the ſoweſt in theſe three
caſes.
By the ſame proceſs I got inflammable air from
Spirit of wine, and about as copiouſly as from the
eſſential
O 3
L
198
OBSERVATIONS ON
Part 1.
eſſential oil of mint. This air continued in water
a whole night, and when it was transferred into
another veſſel was ſtrongly inflammable.
By the ſame proceſs I got inflammable air from
the volatile ſpirit of ſal ainmoniac ; and as I have
obſerved before, the alkaline air which is expelled
from the ſpirit of ſal ammoniac is inflammable.
Endeavouring to procure air from a cauſtic al-
kaline liquor, accurately made for me by Mr. Lane,
and alſo froin ſpirit of falt, I found that the electric
ſpark could not be made viſible in either of them;
ſo that they muſt be much more perfect conductors
of electricity than water, or other fluid ſubſtances.
In all theſe caſes it is probable that the electric
ſpark only gave the ſubſtances the degree of heat
that was neceſſary to give the phlogiſton, and the
water they contained the form of permanent in-
flammable air; for this was done much more effec-
tually by a direct application of heat in the experi-
ments recited in the next ſection.
Inflammable air will ſometimes iſſue ſpontane-
ouſly from oil of turpentine. I once opened a
pint phial, half filled with this kind of oil, and the
cork being very tight, there ruihed out of it a
great quantity of air ; when applying the fame of
a candle to the mouth of the phial, I found the re-
mainder to be ſtrongly inflammable. The oil was
then quite full of air bubbles, and by the heat of
boiling
Seet, II.
199
INFLAMMABLE AIR.
boiling water I'expelled from a quantity of it an
equal bulk of air, all ſtrongly inflammable, like
that which is obtained from metals. It was eight
or ten hours in giving this air. When I could
perceive the colour of the flame, I found it to be
blue.
I then took a quantity of the ſame kind of oil,
which had been kept in another phial, but I found
the air incumbent upon it, within the phial, to be
only common air ; but making it boil in a refort,
I expelled from it twice its bulk of air, all ſtrongly
inflammable. I could not diſtinguiſh the colour of
its flame.
When I had thus expelled all the air which a
quantity of this oil of turpentine ſeemed to contain,
I agitated it very ſtrongly, and frequently, in the
courſe of two days, in order to make it imbibe
more air, that I might expel it again; but I did
not find that it had imbibed more than a very
ſmall quantity, and this, when it came out again,
was only common air ſlightly phlogiſticated. The
firſt boiling had made it brown, and very viſcid.
04
SEC-
1
200
Part I
OBSERVATIONS ON
SECTION
III.
Of the Produktion of inflammable Air from different
Subſtances, by means of Heat and Water.
1
IT
T is probable, that every ſubſtance which con-
tains phiogiſton may be made to yield inflam-
mable air. But for this purpoſe they require dif-
ferent modes of treatment, according to their reſpec-
tive natures. If the ſubſtances be fluid, heat ap-
plied to them directly makes no change in their
conftitution; but when they are made to paſs, in
the form of vapour, through tubes previouſly made
red hot, in which they are neceſſarily expoſed to
a red heat theinſelves, they are readily decompoſed;
and the quantity of inflammable air that was yield-
ed by ſome of them, in this mode of treatment,
appeared to me rather extraordinary.
I began theſe experiments with ſpirit of wine,
having an apparatus proper to receive any water,
or other fluid, that might be formed, or condenſed,
in the proceſs, Pl. VII. fig. 2. From two ounce
meaſures of ſpirit of wine, which was made to paſs in
vapour, through a red hot earthen tube, I got about
1900 ounce meaſures of air, which was all inflammable,
without
1
4
t
į
SeEt. III.
INFLAMMABLE AIR.
201
without any mixture of fixed air in it, and which
burned with a lambent blue flame. Thirty ounce
meaſures of this air weighed eight grains leſs than
an equal quantity of common air. In this proceſs
I collected 0.35 of an ounce meaſure of water.
• In this experiment the air would have weigh-
ed
633 grains
the watery reſiduum 168
801
and the ſpirit of wine would have weighed 821;
ſo that the produce was pretty nearly what might
have been expected from the materials, the nature
of the proceſs conſidered.
I then proceeded to ſubject to the fame proceſs
a quantity of vitriolic ether; and making an ounce
meaſure of it paſs through the hot earthen tube,
almoſt filled with pieces of broken retorts, or cru-
cibles (in order to make a greater quantity of red
hot ſurface) I collected one tenth of an ounce mea-
ſure of water, and 740 ounce meaſures of air, all
inflammable, without any mixture of fixed air. It
burned with a large lambent white flame, like that
of wood in a common fire, and would not explode
with any mixture of dephlogiſticated air. Twenty-
nine ounce meaſures of this air weighed five grains
leſs than an equal bulk of common air.
In the next place, I made ſome vapour of ſpirit
of turpentine paſs through the hot earthen tube, and
procured
202
Part I.
OBSERYATIONS
ON
I
A
procured from it a quantity of inflamınable air,
that was very turbid, like black ſmoke. But the
black matter contained in it was ſoon depoſited
on the ſurface of the water in which it was received.
This alſo contained no fixed air, and burned with
a lambent flame, but much leſs luminous than that
in the preceding experiment. The ſmell of this
air was ſo exceedingly offenſive, that, the appara-
tus being a little deranged, I diſcontinued the
pro-
ceſs before I had aſcertained the quantity of air,
and without collecting any water, which I ſuppoſe
would have been given. Thirty ounce meaſures
of this air weighed eight grains leſs than an equal
quantity of common air,
I did not repeat this experiment with olive oil,
being apprehenſive that the proceſs would be even
more offenſive than that with the ſpirit of, turpen-
tine, and nothing material depending upon it. But,
upon another occaſion, I mixed an ounce of olive
oil with 874 grains of calcined whiting; and ſub-
jecting it to a red heat in an earthen retort, I got
from it near 300 ounce meaſures of air, and ſhould
probably have got much more, if there had been
more whiting in proportion to the oil. The firſt
portion of this air burned with a large white flame;
and the laſt with a ſlight lambent blue one, ex-
actly reſembling the varieties in the proceſs for
extracting air from wood; ſo that there can be no
doubt,
Sect. III.
203
INFLAMMABLE
AIR.
doubt, but that it is the oil in the wood that gives
the air. That excellent philoſopher, Mr. Volta,
was the firſt who hit upon this method, or a ſimilar
one, of getting inflammable air from oil; and he
has given a large account of its peculiar properties.
From other experiments that I made, it appears,
that water is eſſential to the formation of inflam-
mable air. In all the liquid ſubſtances mentioned
above, the water that enters into their compoſition
is ſufficient for the purpoſe; and ſpirit of wine,
and ether, appear to contain more water than is
neceſſary. But when the ſubſtances are dry, and
water does not enter as a neceſſary ingredient into
their compoſition, water muſt be introduced into
the proceſs. This is the caſe with all the metals,
and it is no leſs ſo with fulphur, arſenic, and pro-
bably other ſubſtances of a ſimilar nature, which
mere heat only ſublimes.
Tranſmitting ſteam over a quantity of ſulphur,
which was melting in a hot earthen tube, I pro-
cured from it a quantity of inflammable air, with-
out any fixed air ; and by analyſis it appeared to
be of the fame quality with that which is procured
from iron by oil of vitriol. This proceſs is rather
troubleſome, on account of the fulphur ſubliming,
and filling up the tubes through which the air is
.conveyed.
I then
*
204
Part I.
OBSERVATIONS
ON
I then repeated the ſame proceſs with arſenic,
and from this ſubſtance I procured air in great
pl niy. One ſeventh of it was fixed air, but the
reſt ſtrongly inflammable, and the ſmell of it could
not be diſtinguiſhed from that of phoſphorus.
Twenty ounce meaſures of this air weighed four
grains and a half leſs than an equal quantity of
common air. This experiment was no leſs trou-
bleſome than the preceding, on account of the
arſenic ſubliming, and choking up the tubes.
Having found a very heavy kind of infiamma-
ble air by heating the ſcales of iron mixed with
charcoal, I made the following experiment in or-
der to aſcertain the quantity of air that might be
procured from a given quantity of theſe materials.
Mixing two ounces of the ſcales, or finery cinder
(which I found to be the ſame thing) with one
ounce of perfect charcoal, I got from it, in an
earthen retort, 580 ounce meaſures of air, one tenth
of the firſt part of which was fixed air; but after-
wards it was all inflammable. The ſubſtances
were pretty firmly concreted together, and weighed
1044 grains ; ſo that the loſs of weight was 396
grains, which muſt have been very nearly the
weight of the air procured. Forty ounce meaſures
of this air, freed from all fixed air, weighed two
grains more than an equal quantity of common air.
Beſides
Seef. III.
105
INFLAMMABLE AIR.
Beſides the water, which ſeems to be eſſential
to the conſtitution of inflammable air, this ſpecies
of air readily imbibes more water, which adds
greatly to its ſpecific gravity. This ſeems at leaſt
to be indicated by the following experiment. Fill-
ing a dry bladder with inflammable air, received
immediately from the veſſel containing the iron
and diluted oil of vitriol, from which it was gene-
rated, I found that thirty ounce meaſures of it
weighed more than ſeventeen grains leſs than an
equal bulk of common air ; but when I weighed
that inflammable air of the ſame kind which had
been confined by water in the ſame bladder, it was
only fourteen grains leſs than an equal quantity of
common air. This I repeated ſeveral times with
the fame reſult. This air, therefore, could only
be about three times lighter than common air
whereas the other was more than ten times
lighter.
Having frequently examined the ſpecific gravity
of inflammable air which has been long confined
by water, by weighing it in a bladder, and then
preſſing out the air, and weighing it when empty
(which has the ſame effect as weighing it full of
common air) I have feldom found ſuch air more
than five times lighter than an equal portion of
common air; ſo that the ſpecific gravity of this air is
foon doubled by being kept in theſe crcumſtances.
SEC-
206
Part I
OBSERVATIONS ON:
-
SECTION
IV.
Of Air produced by Subſtances putrefying in Water.
THI
HE experiments recited in this and the fol-
lowing ſection were entered upon chiefly to
diſcover the principle of nutrition in vegetable and
animal ſubſtances; and they ſeem to lead us to
fuppoſe, that this principle is phlogiſton, or the
principle of inflammability, in ſuch a ſtate as to be
capable of becoming, by putrefaction, a true in-
flammable air, but not generally ſuch as to burn
with exploſions, but rather with a blue and lam-
bent flame, mixed with a certain proportion of
fixed air.
In the putrefactive proceſs the phlogiſton is
merely evolved, and not again combined with any
thing, except what may be neceſſary to its af-
ſuming the form of inflammable air; but in
hutrition it is immediately held in folution by the
gaſtric juice, and in the chyle formed by it. But
if any part of the aliment paſs the ſtomach, and
the firſt inteſtines, without having all its phlogiſton
incorporated with the chyle, that principle re-
mains in the excrement, where it is often fet looſe
in
1
Set. IV.
207
INFLAMMABLE AIR.
1
1
in the form of inflammable air, the ſame form that
it would have taken if it had gone through the
ſimple putrefactive proceſs. The phlogiſton of the
aliment, thus entering into the circulation with the
chyle, after anſwering purpoſes in the animal eco-
nomy which are yet very imperfectly known to us,
is thrown out again by means of the blood in the
lungs, and communicated to the air, which is phlo-
giſticated by it.
All alimentary ſubſtances not only contain phlo-
giſton, but I believe are capable of yielding a
proper inflammable air by putrefaction. But in
the following experiments on ſuch vegetables as
are generally uſed for food, roots ſeem to yield it
in a greater abundance than other parts of plants ;
but there are fome remarkable differences among
them in this reſpect. For though potatoes are
exceedingly favourable to the growth of that
green vegetable ſubſtance, which yields pure air
fo copiouſly, owing probably to the phlogiſton
they contain, onions, perhaps equally nutritive with
potatoes, are exceedingly unfriendly to that plant ;
but then they yield inflammable air in an aſtoniſh-
ing quantity, when they are left to putrefy in water.
This I rather ſuſpect is a proof, that onions con-
tain more phlogiſton, and are the more nutritive
ſubſtance, of the two.
On
208
Part I.
OBSERVATIONS ON
On the 28th of June I expoſed to the ſun
eighteen penny-weights of onions, in a jar of an
hundred ounces of river water, inverted in a baſon of
the ſame. They preſently began to yield air, but
without ever becoming green; and on the 15th
of July the quantity was fifteen ounce meaſures,
a ſmall part of which was fixed air, and the reſt
ſtrongly inflammable. The water was white and
turbid, and the air had a ſtrong ſmell of onions.
About the ſame time I obſerved that it made
no difference, with reſpect to the quality of this
air, whether the onions were placed in the light or
in the dark, the principle of vegetation not being
concerned in this caſe. And though I obſerved
the following differences in the quantities of air
produced in the ſun and in the ſhade, they were
not uniform, and therefore muſt have depended
upon
fome unknown accidental circumſtances.
On the 17th of July I put two onions, each
weighing an ounce and a quarter, in the ſun, and
two others of the fame ſize, in a ſimilar jar in
the dark: On the 23d I examined them, and
had twenty four ounce meaſures of air in the ſhade,
and only twelve from thoſe in the ſun; but the
latter was more ſtrongly inflammable than the
former, which burned with more of a lambene
flame, though both exploded in ſome meaſure, fo
I
as
1
1
Seet. IV.
209
INFLAMMABLE
AIR.
as to be ſomething more inflammable than air from
marſhes.
Having kept a quantity of this air, from the
tiine, above-mentioned to the 20th of July, 1780,
I found it then ſtrongly inflammable, little inferior
to the inflammable air from metals. Perhaps the
fixed air, which had been mixed with it before,
was now completely expelled from it. It appears,
however, that this kind of inflammable air has an
inflammability of as permanent a nature as 'any
whatever. The air from marſhes alſo, which, with
Sig. Volta, I doubt not comes from putrefying
vegetable ſubſtances, I have alſo found to be equally
permanent.
On the iſt of Auguſt I took two halves of the
ſame onion (which was an old one, and beginning
to ſprout) each half weighing ſeventeen penny-
weights twelve grains, and I placed one of them
in the ſun, and the other in the ſhade, both in
ſimilar receivers. On the 24th of the fame month,
that in the ſun had given an ounce meaſure and
three quarters of air, of which one fifth was fixed
air, and the reſt inflammable. From that in the
dark I took two ounce meaſures and a quarter of air,
one third of which was fixed, and the reſt infiam-
mable. From theſe experiments I was ready to
conclude, that onions and therefore, probably,
other vegetable ſubſtances) would always give more
Vol. I,
P
air
1
210
Part I.
OBSERVATIONS ON
1
air in the dark than in the light; but the follow-
ing experiments ſhewed that this is by no means
the caſe always.
The 30th of July I placed in the ſun, in a vef-
ſel containing fifty ounces of water, a part of a freſh
gathered onion, weighing nine penny-weights, and
alſo another part of the ſame onion, and of the
fame weight, in a vefſel of the ſame fize in the
dark. On the 24th of Auguſt that in the ſun had
yielded three ounce meaſures of air, all inflam-
mable, and that in the dark had produced as nearly
as poſſible the ſame quantity, and as infiammable,
when the fixed air that was mixed with it was
waſhed out of it. The fixed air which had been
extricated in the fun had been diſſipated by means
of the free acceſs of freſh air.
Upon a former occaſion I got only fixed air
from onions confined by quickſilver ; but then they
wanted moiſture, or were not kept till they were
properly putrid. For I have ſince got inflamma-
ble air, as well as fixed air, from onions kept in
quickſilver, from the 2d of September, 1779, to
the 31ſt of March, 1780. The onions weighed
twelve penny-weights twenty grains, and the air
was half an ounce meaſure, three fourths of which
was fixed air, and the reſt inflammable. It appears
from this, as well as from many other obſervations
which I ſhall have occaſion to mention hereafter, that
neither
1
A
Seet. IV.
211
INFLAMMABLE AIR.
1
*
neither fixed air, inflammable air, or nitrous air,
can be produced without a conſiderable quantity of
water, part of which we may therefore, with great pro-
bability, infer enters into the compoſition of theſe kinds
of air; though when they are formed, we may not
know any method of diſcovering, and re-producing
that water.
Both carrots and parſnips yield great quantities
of inflammable air, and equally in the fun or in
the ſhade. I was at one time much amuſed with
obſerving the inflammable air iſſuing from one of
the carrots in the ſun. It came ſometimes in a
conſtant ſtreamn, or in large ſucceſſive bubbles,
from one particular place, neither at the centre,
nor near the outſide of the carrot, but in the place
where the air holes are the largeſt.
To aſcertain the quantity of air produced from
a given weight of theſe two roots, I placed as much
of a parſnip as, by expelling water from a cylindri.
cal veſſel, I found to occupy the ſpace of two
ounce meaſures and a quarter of water, in the ſun ;
and the next day I took from it four ounce mea-
fures of air, all fixed air, the reſiduum extinguiſh-
ing a candle. This was on the 29th of July, and
on the 31ſt of the ſame month I took from it four
ounce meaſures more, of which two thirds of an
ounce meaſure was inflammable. On the 2d of
Auguſt I again took from it four ounce meaſures,
1
P2
one
1
.
212
Part 1.
OBSERVATIONS
ON
1
one fourth of which was inflammable, exploding
with a blue flame. Laſtly, on the 24th of Auguſt,
perceiving that no more air would be produced,
I took from it one third of an ounce meaſure;
one third of which was fixed air, and the reſt not
inflammable, but phlogiſticated.
From carrots occupying the ſpace of an ounce
meaſure and a half of water, expoſed to the ſun in
rain water, from the 26th to the 31ſt of July, I
took ten ounce meaſures of air, of which an ounce
meaſure and half was ſtrongly inflammable, ex-
ploding with a red flame; and on the 4th of
Auguſt I took from them near four ounce meaſures
of air, of which more than one half was inflam-
inable. The water, which had a large ſurface,
had probably abſorbed much of the fixed air.
This, however, was all the air that theſe carrots
would yield.
An equal weight of carrots, expoſed the ſame
time in the dark, yielded nearly the ſame quantity
of air, but only a ſmall proportion of it was in-
fiammable. This, however, I do not attribute to the
darkneſs, but to ſome other unknown circumſtance.
A Niced turnip freſh gathered, weighing near
three ounces, expofed in the ſun in rain water,
yielded twelve ounce meaſures of air, one third
of which was fixed air, and the reſt ſtrongly in-
Dammable.
On
+
1
1
SCEZ. IV. INFLAMMABLE AIR. 213
fixed air
On the 30th of July two ounces of turnip,
freſh gathered, were placed in the dark, in a vef-
ſel containing feventy ounce meaſures of water;
and on the 24th of Auguſt I took from it an
ounce meaſure and a quarter of air, of which one
ounce meaſure was phlogiſticated, not inflamma-
ble. The water was exceedingly offenſive. This
phlogiſticated air had been, I doubt not, inflam-
mable in its origin, and in much greater quantity.
When a turnip was ſliced very thin, and the quan-
tity of water large, I ſhall obferve, that dephlogiſti-
cated air is produced.
Fruits, I found by no means favourable to the
production of pure air. Like the preceding roots,
they putrefied, and yielded inflammable air, mixed
with fixed air. . From peaches, both in the ſun and
in the ſhade, I got air, three fourths of which was
occaſion the quantity of air produced in the ſun
was twice as much as that produced in the ſhade;
though the quantity of water in which they were
expoſed was the ſame, and the peaches themſelves
were, as far as I could perceive, of the ſame ſize,
and in the ſame ſtate.
I placed two Morella cherries, one in the fun,
and the other in the ſhade, in equal veſels of
water. From that in the fun I got one third of
P 3
an
1
I14
Part 1.
OBSERVATIONS
ON
an ounce meaſure of air, and from that in the
ſhade one fifth of an ounce meaſure, both infiam-
mable. I had the ſame reſult with apricots.
Having found the capacity of theſe nutritive
ſubſtances to yield inflammable air, I next tried
whether they would part with any of it in boiling.
But I found that none of them did, but only in
putrefying afterwards ; ſo that this mode of prepara-
tion (and the famé I doubt not would be found
to be the caſe with roaſting, &c.) does not deprive
any of theſe aliments of any part of their nutritive
power.
From nineteen penny-weights eighteen grains of
onions I expelled, by boiling in river water, half
an ounce meaſure of air, of which one third
was not abſorbed by water, and extinguiſhed a
candle.
From one ounce fifteen penny-weights of let-
tuce I got three quarters of an ounce meaſure of
air, of which half an ounce meaſure was phlo-
giſticated air.
From one ounce ſixteen penny-weights twelve
grains of carrots I got three quarters of an ounce
meaſure of air, of which about one ounce meaſure
was phlogiſticated air.
Theſe differences are inconſiderable, and ſome
of the air, no doubt, came from the water in
which
Sect. IV.
TIS
INFLAMMABLE AIR.
which theſe ſubſtances were boiled. Afterwards
the potatoes and carrots, putrefying in water,
yielded each more than two ounce meaſures of
air, one half of which was fixed air, and the
reſt inflammable. The onions yielded only about
half an ounce meaſure of air, but it was of the
fame kind, and the lettuce gave only a tenth of
of an ounce meaſure, in which nothing could be
perceived to be inflammable. But I did not
begin to collect this air till a day or two af-
ter the proceſs of boiling, when I perceived
ſome of the ſubſtances to be in a ſtate of yield-
ing air.
P4
SEC-
A
216
Part I.
OBSERVATIONS OY
1
SECTION
V.
Of Air produced by various Subſtances putrefying in
Quickſilver.
IN ſome of the firſt of my experiments I amuſed
myſelf with putting different vegetable and ani-
mal ſubſtances into tall glaſs veſſels, previouſly filled
with mercury, and the following were among the
reſults which I then noted.
If beef or mutton, raw or boiled, be placed ſo near
to the fire, that the heat to which it is expoſed ſhall
equal, or rather exceed, that of the blood, a conſider-
able quantity of air will be generated in a day or
two, about one ſeventh of which I have generally
found to be abſorbed by water, while all the reſt was
inflammable: but air generated from vegetables, in
the fame circumſtances, will be almoſt all fixed air,
and no part of it inflammable. This I have re-
peated again and again, the whole proceſs being in
quickſilver; ſo that neither common air, nor water,
had
any
acceſs to the ſubſtance on which the experi-
ment was made; and the generation of air, or efflu-
vium of any kind, except what might be abforbed
by quickſilver, or reſorbed by the ſubſtance itſelf,
might be diſtinctly noted.
1
A veget-
t
SeET. V.
217
INFLAMMABLE AIR.
A vegetable ſubſtance, after ſtanding a day or two
in theſe circumſtances, will yield nearly all the air
that can be extracted from it, in that degree of heat;
whereas an animal ſubſtance will continue to give
more air or effluvium, of ſome kind or other, with
very little alteration, for many weeks. It is re-
markable, however, that though a piece of beef or
mutton, plunged in quickſilver, and kept in this
degree of heat, yield air, the bulk of which is in-
flammable, and contracts no putrid ſmell (at leaſt, in
a day or two) a mouſe treated in the fame manner,
yields the proper putrid effluvium, as indeed the
ſmell ſufficiently indicates.
By means of theſe experiments, and thoſe in the
preceding ſection, it may be poſſible to determine
the nutritive powers of different vegetable and ani-
mal ſubſtances, and alſo other problems in philo-
ſophy; though too much muſt not be expected
from them.
It might have been imagined, that by this means
we ſhould be able to aſcertain the quantity of air
that any maſs of putreſcent matter would thoroughly
phlogiſticate. For any given quantity of infam-
mable air will completely phlogiſticate twice its
bulk of common air. But it will be found that a
putrefying mouſe will phlogiſticate much more than
that proportion of air. There muſt, therefore,
be much more phlogiſton in a mouſe than
forms
i
1
h
218
OBSERVATIONS ON:
Part I.
forms the inflammablc air which comes from it.
Perhaps, therefore, that phlogiſton which contributes
to animal nutrition, may alſo be more than that
which enters into the compoſition of the inflammable
air that comes from the putrefying ſubſtance. This
is a ſubject that requires and deſerves much farther
inveſtigation. I only recite the following as leading
experiments, to the ſolution of greater problems.
They are, indeed, upon too ſmall a ſcale to be of
much uſe even for this purpoſe; except to thew
that the ſame kind of ſubſtance, which in a large
quantity yields inflammable air, in a ſmall quantity
may yield phlogiſticated air.
A ſmall fiſh, weighing forty four grains, being
confined in quickſilver from the 21ſt of May to the
24th of Auguſt, gave ſomething more than half an
ounce meaſure of air, two thirds of which was fixed
air, and the remainder extinguiſhed a candle, but
was not ſenſibly, inflammable.
From two pennyweights of well boiled beef I got
a very ſmall quantity of air, the bulk of which was
fixed air, and the reſt not inflammable. At another
time, from one pennyweight and nineteen grains of
raw beef, I got 0.22 of an ounce meaſure of air, nine
tenths of which was fixed air, and the reſt extin-
guilhed a candle.
From fifty-three grains of raw lamb, I got 0.17
of an ounce meaſure of air, the bulk of which was
fixed
»
Seet. V.
219
INFLAMMABLE. AIR.
A
1
fixed air, and the reſt not ſenſibly infiammable: but
from two pennyweights and two grains of well
roaſted lamb, I got three quarters of an ounce mea-
ſure of air, half of which was fixed air, and the reſt
highly inflammable; and ſome time after I took
from the ſame ſubſtance half an ounce meaſure of air
more, of which three fourths was fixed air, and the
reſt inflammable.
From thirteen pennyweights and four grains of
the tendor of a roaſted neck of veal, I got an ounce
meaſure and half of air, of which half was fixed air,
and the reſt phlogiſticated. Afterwards I took from
it one ounce meaſure and three quarters of
pure
fixed air, with the ſmalleſt reſiduum poſſible. In
the former experiment alſo, as well as on a former
occaſion, I found that the inflammable air was
extricated firſt, and a long time before all the fixed
air was exhauſted.
Having had occaſion to make many experiments
with putrefying mice, and having more in proſpect,
I was particularly deſirous to aſcertain the quantity
and quality of the air produced by a mouſe of the
middle ſize putrefying in quickſilver, and I found as
follows. A mouſe weighing ſix pennyweights and
three grains, confined by quickſilver, which had pu-
trefied from the 8th of April, had yielded on the
24th of July one ounce meaſure and three quarters
3
of
7
2.0
Part, I.
OBSERVATIONS ON
of air, of which one fourth was weakly inflammable,
and the reſt fixed air. This I found, by other expe-
riments, was nearly as much as a mouſe would yield
in theſe circunſtances.
Having left another mouſe to putrefy in quick-
ſilver, I took the air produced from it at different
times, in order to ſatisfy myſelf more fully with
reſpect to the proportion that the fixed and inflam-
mable air bore to each other, from the beginning to
the end of the proceſs. The mouſe weighed five.
pennyweights and ten grains, and it was put into an
inverted veſſel of quickſilver on the 13th of June.
On the 26th of that month, I took from it near an
ounce meaſure of air, three fourths of which was
fixed air, and the reſt inflammable, burning with a
very blue flame. On the 16th of Auguſt I took
from it an ounce meaſure and a quarter of air, of
which four fifths was fixed air, and the reſt, if it was
inflammable at all, was ſo in the ſlighteſt degree
imaginable; and laſtly, on the 3d of April follow-
ing, I took from it a ſmall quantity of air, perhaps
one tenth of an ounce meaſure, the whole of which
was, as far as I could judge, all fixed air.
When a mouſe is left to putrefy in this manner,
there comes from it a great quantity of diſſolved
blood, or ſome other thin reddiſh liquor. This I
carefully ſeparated from what was folid in the mouſe,
and
Sect. V.
221
INFLAMMABLE AIR.
and found that this continued to give air, when the
liquor gave little or none; ſo that perhaps it may be
ſomething ſolid in all bodies that contributes to the
formation of permanent air. By long ſtanding,
however, I did get a little air from this red liquor,
and it was almoſt all fixed air. It was, perhaps,
combined with it, at its ſeparation from the mouſe.
The experiments on ſome of the different parts
and fecretions of animal bodies were made on the
fame ſmall ſcale with moſt of the preceding, and
therefore they can only have the ſame imperfect uſe.
From ſeven pennyweights of the medullary part
of a ſheep's brain raw, I got four and a half ounce
meaſures of air, of which one fifth part of an ounce
meaſure was inflammable, and the reſt fixed air. I
alſo found by ſimilar experiments, that the cortical
part of the fame brain gave ſomewhat leſs air than
the medullary part; but the proportion of the in-
flammable to the fixed air was the fame. No cer-
tain inference, however, can be drawn from experi-
ments on ſo ſmall a ſcale as theſe.
Two pennyweights of mutton gravy yielded 0.02
of an ounce meaſure of air, the greateſt part of
which was fixed air, and the remainder ſeemingly
inflammable.
Two pennyweights of the craſamentum of ſheep's
blood gave only a ſmall bubble of air, too ſmall to
be examined. The ferim alſo yielded ſome air, the
bulk
4
222
Part I.
OBSERVATIONS
ON
bulk of which was fixed air, and the reſt phlogiſti-
cated.
An ounce meaſure of milk yielded near half an
ounce meaſure of air, almoſt pure fixed air, a ſmall
remainder being phlogiſticated.
An ounce meaſure and an half of the bile of a
ſheep yielded half an ounce meaſure of air, almoſt
all fixed air, the ſmall reſiduum being phlogiſticated.
I ſhould not have made theſe experiments on fo
very ſmall a ſcale, but that I expected a greater
quantity of air from all the ſubſtances, and becauſe
leſs quickſilver was wanted for the purpoſe; ſo that
I could have more proceſſes going on at the ſame
time. Had the fame ſubſtances putrefied in water,
they would have yielded many times more air,
water appearing to be an eſſential ingredient in the
conftitution of inflammable air.
PART
1
1
Seft. I.
223
INFLAMMABLE AIR.
PART II.
OF THE PROPERTIES, OF INFLAMMABLE AIR.
SECTION
I..
Various Experiments to change and decompoſe inflam-
inable Air.
1. Inflamınable Air diminiſhed by Charcoal.
1
IN
N purſuance of the Abbé Fontana's experi-
ment on the abſorption of air by charcoal,
I dipped pieces of hot charcoal into a phial of in-
Hammable air, and immediately inverted it in quick-
ſilver. When one third of the whole quantity was
imbibed, I found that both the remainder, and
that which was again expelled from the charcoal,
by plunging it in water, was inflammable; the
former not to be diſtinguiſhed from what it had
been, but the latter a little leſs inflammable.
Of
224
Part II.
OBSERVATIONS ON
2. Of Putrefa&tion in inflammable Air.
Though air tainted with putrefaction extin-
guiſhes fame, I have not found that animals or
vegetables putrefying in inflammable air render it
lefs inflammable. But one quantity of inflamma-
ble air, which I had ſet by in May, 1771, along
with the others above-mentioned, had had ſome
putrid fleſh in it; and this air had loſt its inflamma-
bility, when it was examined at the ſame time
with the other in the December following. The
bottle in which this air had been kept, ſmelled
exactly like very ſtrong Harrogate water. I do
not think that any perſon could have diſtinguiſhed
them.
3. Plants growing in inflammable Air.
I have made plants grow for ſeveral months
in inflammable air made from zinc, and alſo from
oak; but, though they grew pretty well, the air
ſtill continued inflammable. The former, indeed,
was not ſo highly inflammable as when it was
freſh made, but the latter was quite as much ſo;
and the diminution of inflammability in the foriner
cafe, I attribute to ſome other cauſe than the growth
of the plant.
Water
+
Seft. I.
225
INFLAMMABLE AIR:
1
4. Water impregnated with infiammable Air.
re
Neither does inflammable air undergo any
change by impregnation with water, in which re-
ſpect, it agrees with what I have obſerved of
nitrous air. For having impregnated a quantity
of rain water (out of which all its air had been
carefully extracted by the air pump) with inflam-
mable air, of which it imbibed about one thirteenth
of its bulk; about a month afterwards, by making
it boil in a phial, I expelled from it about the
ſame quantity of air, and found it to be as ftrongly
inflammable as it had ever been. After this
pro.
ceſs there was a depoſit from the water of a filmy
kind of matter, probably the earth of the metal
that had been employed in producing the inflam-
mable air. In both theſe reſpects inflammable
air reſembles nitrous air.
Having had the curioſity, on the 25th of July,
1772, to expoſe a great variety of different kinds
of air to water out of which the air it contained
had been boiled, without any particular view; the
reſult was, in ſeveral reſpects, altogether unexpect-
ed, and led to a variety of new obſervations on
the properties and affinities of ſeveral kinds of air
with reſpect to water. Among the reſt three
fourths of that which was inflammable was ab-
Vol. I.
forbed
Q
226
Part II.
OBSERVATIONS ON
1
forbed by the water in about two days, and the
remainder was infiammable, but weakly ſo.
Upon this, I began to agitate a quantity of
ſtrong inflammable air in a glaſs jar, ſtanding in
a pretty large trough of water, the ſurface of
which was expoſed to the common air, and I
found that when I had continued the operation
about ten minutes, near one fourth of the quantity
of air had diſappeared ; and finding that the re-
mainder made an efferveſcence with nitrous air,
I concluded that it muſt have become fit for re-
ſpiration, whereas this kind of air is, at the firſt,
as noxious as any other kind whatever. To aſcer-
tain this, I put a mouſe into a veſſel containing
two ounce meaſures and a half of it, and obſerved
that it lived in it twenty minutes, which is as long
as a mouſe will generally live in the ſame quantity
of common air. This mouſe was even taken out
alive, and recovered very well. Still alſo the air
in which it had breathed ſo long was inflammable,
though very weakly fo: I have even found it to
be ſo when a inouſe has actually died in it. In-
flammable air thus diminiſhed by agitation in
water, makes but one exploſion on the approach
of a candle, exactly like a mixture of inflamma-
ble air with common air.
From this experiment I concluded that, by con.
tinuing the ſame proceſs, I ſhould deprive inflam-
mable
Sect. l.
227
INFLAMMABLE AIR;
+
mable air of all its inflammability, and this I
found to be the cafe; for, after a longer agitation,
it admitted a candle to burn in its like common
air, only more faintly; and indeed by the teſt of
nitrous air it did not appear to be near ſo good
as common air. Continuing the ſame proceſs ſtill
farther, the air which had been moſt ſtrongly in-
flammable a little before, came to extinguiſh a
candle, exactly like air in which a candle had burn-
ed out, nor could they be diſtinguiſhed by the teſt
of nitrous air.
I took ſome pains to aſcertain the quantity of
diminution, in freſh made and very highly inflamma-
ble air from iron, at which it ceaſed to be inflamma-
ble, and, upon the whole, I concluded that it was
fo when it was diminiſhed a little more than one
half: for a quantity which was diminiſhed exactly
one half had ſomething inflammable in it, but in
the fighteſt degree imaginable. It is not impro-
bable, however, but there may be great differences
in the reſult of this experiment.
This change in the inflammable air proceeded,
I doubt not, from its communication with the
external air through the water; ſo that I ſhould
not expect the ſame change from the agitation
of it in cloſe veſels. Phlogiſticated air is meli-
orated by agitation in open veſſels, but not in
cloſe ones.
Q2
Finding
1
1
228
Part II
OBSERVATIONS ON
:
Finding that water would imbibe inflammable
air, I endeavoured to impregnate water with it,
by the ſame proceſs by which I had made water
imbibe fixed air ; but though I found that diſtilled
water would imbibe about one fourteenth of its
bulk of inflammable air, I could not perceive
that the taſte of it was ſenſibly altered.
5. Inflammable Air agitated in Oil of Turpentine.
1
The effect of agitating inflammable air in
oil of turpertine, and alſo in ſpirit of wine, is not
a little remarkable. They ſeem to bring it at
laſt to the ſame ſtate to which it is brought by
agitation in water, only that, whereas it is diminiſhed
by the proceſs in water, it is increaſed in theſe
proceſſes. Both theſe ſubſtances, however, as well
as water, ſeem to deprive this air of part of its
phlogiſton. The facts, as I obſerved them, were
as follows.
Having agitated a quantity of inflammable air
in oil of turpentine, I preſently obſerved an in-
creaſe of its quantity, and I continued the proceſs
till it had increaſed one half. Agitation in ſpirit
of wine produced the ſame effect, but more time
was requiſite for it. Allowing it to continue in
theſe circumſtances all night, I found that one half
of the additional quantity of air had diſappeared :
but
7
Sect. I.
229
INFLAMMABLE
AIR
but by repeating the agitation about a quarter of
an hour, it was again increaſed as much as before.
I then examined it, and found that it was not in
the leaſt abſorbed by water, did not affect lime
water, was but very ſlightly inflammable, and was
diminiſhed by nitrous air almoſt as much as com-
mon air; which is in all reſpects the very ſtate
to which agitation in water would have brought
it, except that in water it would have been con-
ſiderably diminiſhed, inſtead of being increaſed..
I agitated another quantity of inflammable air
in oil of turpentine made pretty warm, but the
effect was the very ſame as when it was cold. In
this caſe, however, though I hardly ever diſcon-
tinued the agitation, after I had begun it, when it
had gained an increaſe of about one fourth of its
bulk, it loſt it again, and was reduced to its
original dimenſions. I then examined it, and
found it to burn with a lambent blue flame. I
own myſelf to be intirely at a loſs to account for
the increaſe and decreaſe of the quantity of air
in theſe experiments.
6. Animals dying in inflammable Air.
Inflammable air kills animals as ſuddenly as
fixed air, and, as far as can be perceived, in
the ſame manner, throwing them into convulſions,
Q3
and
230
Part II.
OBSERVATIONS ON
1
ز
and thereby occaſioning preſent death. I had
imagined that, by animals dying in a quantity of in-
Aammable air, it would in time become leſs noxious;
but this did not appear to be the caſe; for I killed
a great number of mice in a ſmall quantity of
this air, which I kept ſeveral months for this pur-
poſe, without its being at all fenſibly mended;
thc laſt, as well as the firſt mouſe, dying the mo-
ment it was put into it.
7. Inflammable Air changed by keeping in Water.
may be
Inflammable air is not thought to be miſ-
cible with water, and when kept many months,
ſeems, in general, to be as inflammable as ever,
Indeed, when it is extracted from vegetable or
animal ſubſtances, a part of it will be imbibed by
the water in which it ſtands; but it
pre-
ſumed, that in this caſe, there was a mixture of
fixed air extracted from the ſubſtance along with
it. I have indiſputable evidence, however, that
inflammable air, ſtanding long in water, has actu-
ally loſt all its inflammability, and even come to
extinguiſh fame much more than that air in
which candles have burned out. After this change
it appears to be greatly diminiſhed in quantity,
and it ſtill continues to kill animals the moment
they are put into it.
This
Sect. I.
231
INF-L AMMABLE AIR.
ſet by.
This very remarkable fact firſt occurred to my
obſervation on the 25th of May, 1771, when I
was examining a quantity of inflammable air,
which had been made from zinc, near three years
before. Upon this, I immediately ſet by a com-
mon quart bottle filled with infiammable air from
iron, and another equal quantity from zinc; and
examining them in the beginning of December
following, that from the iron was reduced near one
half in quantity, if I be not greatly miſtaken; for
I found the bottle half full of water, and I am
pretty 'clear that it was full of air when it was
That which had been produced from
zinc was not altered, and filled the bortle as
at firſt.
I think that, in all, I have had four inſtances
of inflammable air loſing its infiammability, while
it ſtood in water.
ſt is very poſſible, however,
that there might be ſome impregnation in this
water, of which I was not aware, ſince other perſons,
I find, have not found any change in inflammable
air by keeping it in pure water.
November 6, 1772, a quantity of inflammable
air, which, by long keeping, had come to extin-
guilh Alame, I obſerved to ſmell very much like
common air in which a mixture of iron filings and
brimſtone had ſtood. It was not, however, quite
ſo ſtrong, but it was equally noxious.
Q.4
The
232
Part IT,
OBSERVATIONS ON
8. The elettric Spark in inflammable Aįr.
No kind of air, on which I have yet made
the experiment, will conduct electricity; but the
colour of an electric ſpark is remarkably different
in ſome kinds of air, which ſeems to ſhew
that they are not equally good non-conductors.
In fixed air, the electric ſpark is exceedingly
white; but in inflammable air it is of a purple,
or red colour. Now, ſince the moſt vigorous
ſparks are always the whiteſt, and, in other caſes,
when the ſpark is red, there is reaſon to think that
the electric matter paſſes with difficulty, and with
lefs rapidity: it is poſſible that the inflammable air
may contain particles which conduct electricity,
though very imperfectly; and that the whiteneſs
of the ſpark in the fixed air, may be owing to
its meeting with no conducting particles at all.
When an exploſion was made in a quantity of
inflammable air, it was a little white in the center,
but the edges of it were ſtill tinged with a beau-
tiful purple. The degree of whiteneſs in this caſe
was probably owing to the electric matter ruſhing
with more violence in an exploſion than in a com-
mon ſpark.
9. The smell of inflammable Air,
Infiammable air, when it is made by a quick
proceſs, has a very ſtrong and offenſive ſmell,
from
1
1
Seet. I.
1
233
INFLAMMABLE AIR.
- +
1
-
from whatever ſubſtance it be generated; but this
ſmell is of three different kinds, according as the
air is extracted from mineral, vegetable, or animal
ſubſtances. The laſt is exceedingly fetid; and it
makes no difference, whether it be extracted from
a bone, or even an old and dry tooth, from ſoft
muſcular fleſh, or any other part of the animal.
The burning of any ſubſtance occaſions the ſame
ſmell: for the groſs fume which ariſes from them,
before they Aame, is the inflammable air they
contain, which is expelled by heat, and then readily
ignited. The ſmell of inflammable air is the very
fame, as far as I am able to perceive, from what-
ever ſubſtance of the fame kingdom it be extract-
ed. Thus it makes no difference whether it be
got from iron, zinc, or tin, from any kind of wood,
or, as was obſerved before, from any part of an
animal.
If a quantity of inflammable air be contained in
a glaſs veſſel ſtanding in water, and have been
generated very faſt, it will ſmell even through the
water, and this water will alſo foon become cover-
ed with a thin film, aſſuming all the different
colours. If the inflammable air have been gene-
rated from iron, this matter will appear to be a
red ochre, or the earth of iron, as I have found by
collecting a conſiderable quantity of it; and if iç
have
234
OBSERVATIONS ON. Part II.
A
have been generated from zinc; it is a whitiſh
ſubſtance, which I ſuppoſe to be the cals of the
metal. It likewiſe ſettles to the bottom of the
veffel, and when the water is ſtirred, it has very
much the appearance of wool. When water is
once impregnated in this manner, it will continue
to yield this fcum for a conſiderable time after
the air is removed from it. This I have often
obſerved with reſpect to iron.
SECTION
II.
Inflammable Air decompoſed by Heat, in Tubes of
Flint Glaſs.
1
TH
HIS kind of air remains unchanged when
it is expoſed to heat in a tall jar of flint
glaſs, in which it had free liberty to expand.
I made this experiment at the ſame time with the
fimilar one that I ſhall have occaſion to mention on
nitrous air. This air, as well as the nitrous, re-
covered its former dimenſions when it was cold,
and appeared to be unchanged in its quality.
A very
u
SeEt. II.
235
INFLAMMABLE AIR.
-
A very ſingular decompoſition of inflamma-
ble air I obſerved in conſequence of expoſing a
great variety of ſubſtances to the influence of a
ſand heat, which I kept up for ſeveral months.
Among other things, I buried in this hot fand
glaſs tubes hermetically ſealed, and previouſly filled
with all the different kinds of air. I filled them
in the following manner.
Having provided myſelf with glaſs tubes about
four feet long, and about one third or one half
of an inch in diameter, and of ſuch a thickneſs
as that I could eaſily melt them with the flame
of a couple of candles and a common blow pipe,
I firſt ſealed the tubes at one end, then filled them
with quickſilver, and placed them inverted in a
baſon of the faine. After this, either transferring
the air in a bladder, from the jars in which they
had been ſtanding in water, or generating the air
a-freſh, if it was of a kind not to bear the con-
tact of water, I filled the tubes, completely with
the kinds of air on which I wiſhed to make the
experiment, diſplacing the quickſilver. This be-
ing done, I inclined the tube, and applying the
flame of my candles with ſome care (holding the
blow pipe in my mouth only, and keeping firm
hold of the tube on each ſide of the place to
which I was applying the heat) I melted the glaſs,
and took off what lengths of it I pleaſed; and
every
1
236
OBSERVATIONS ON
Part II.
every piece was, of courſe, hermetically ſealed.
Theſe pieces I marked with a file, keeping an
account of the meaning of the marks, that when
I took them out of the fand, I might preſently
know with what kind of air they had been filled.
When I was performing this part of the pro-
ceſs with inflammable air in Aint glaſs tubes, 'I
obſerved that the places to which I applied the
heat were generally tinged black ; but I gave lit-
tle attention to this circumſtance, thinking it might
be fomething accidental; and without any parti-
cular expectation, I buried theſe tubes in the ſand,
together with the others. This was on the 25th
of September, 1777.
On the 20th of January following, I examined
theſe tubes, together with every thing elſe that had
been expoſed to the ſame heat.
The tube con-
taining the inflammable air was ten inches long,
and by ſome accident was broken; but it was jet
black throughout. At this I was very much ſur-
prized, but I did not then ſuſpect that it was at
all owing to the inflammable air with which it had
been filled; thinking it might have been occaſion-
ed by ſome phlogiſtic matter in the ſand, or in
ſome of the veſſels that had burſt in its neigh-
bourhood.
Reflecting, however, on this odd circumſtance,
and thinking, from the uniformity of the tinge,
that,
1
1
SCET. II:
237
INFLAMMABLE AIR.
1
that, poſſibly, it might have been occaſioned by the
inflammable air, I filled another ſmall glaſs tube with
the ſame air ; and, ſealing it hermetically, buried it
deep in fand, contained in an iron pot, which I ſet on
the fire, and made very hot, nearly red; and taking
it out the next day, I found the tube quite black,
except a ſmall part on one ſide of that end which
had been uppermoſt, about two inches higher than
the other, and which, conſequently, had not been
expoſed to fo great a degree of heat.
Being now fully ſatisfied that the blackneſs of the
tube was certainly occaſioned by heating the inflam-
mable air within it, in circumſtances in which it could
not expand, I proceeded to examine the ſtate of the
air, and frequently found it to be inflammable; but,
in general, the quantity was too ſmall to make a fa-
tisfactory experiment.
Putting two glaſs tubes, about four inches in
length, and a quarter of an inch in diameter, into a
fard furnace, I kept them in it two days ; when I
took them out, and obſerved that the tube which I
had placed at the bottom of the fand, in the greateſt
degree of heat, was nearly melted, and perfectly blue,
like indigo; while the other tube, which had not
been expoſed to ſo great a degree of heat, was of a
beautiful jet black throughout.
At one time I had a ſuſpicion that this blackneſs
communicated to the glaſs was ſomething precipi-
tated
!
4
238
Part 1
OBSERVATIONS ON
tated from the iron, by the folution of which the
inflammable air had been made; but I was ſoon
convinced of the contrary, by finding that the effect
was the very fame when the inflammable air was
made from zinc.
I ſoon found that there was no occaſion for ſo long
a proceſs to produce this effect, at leaſt upon the
glaſs. For it begun to be diſcoloured the moment
it was red hot, or rather when it became foft; as
was evident by holding one of the tubes in an open
fire, or in the flame of a candle. For wherever
the heat was applied, the blackneſs immediately
took place, without affecting any other part of the
tube.
When I examined this black tinge narrowly, I
found that it did not penetrate the glaſs, but formed
a delicate fuperficial tinge, leaving the glaſs as per-
fe&ly poliſhed as before the proceſs. But the black-
neſs was indelible; at leaſt, it could not be ſcraped
off without tearing the ſurface of the glaſs, and it
made no change in it with reſpect to electricity.
For the tube thus blackened was as perfect a non-
conductor as ever.
The blue colour of the glaſs that was moſt heated,
Mr. Delaval informed me, was owing to ſomething
of iron in the compoſition of the glaſs. That it alſo
depended upon the degree of heat, I aſcertained by
placing one of theſe tubes in a vertical poſition in the
fand
I
Seết. II.
239
INFLAMMABLE AIR.
fand heat. For the lower end of the tube, which
was moſt heated, had acquired a deep blue colour,
and it paſſed into the black at the upper end of the
tube without any intermediate colour. There was
alſo no other colour higher than the black; fo that
the firſt tinge that the glaſs receives is a perfect
black. Yet viewing the firſt tinge that it receives
by the light of a candle placed beyond it, it ſeemed
to have a ſhade of red.
As I was ſenſible that the blackneſs was owing to
the precipitation of phlogiſton from the inflammable
air, I thought it poſſible that ſome ſubſtance which
had a near affinity with phlogiſton might diſcharge
it; and trying minium, it ſucceeded immediately.
Having filled one of theſe black tubes with this
metallic calx, the moment I made it red hot, the
blackneſs intirely diſappeared, and left the tube as
tranſparent as ever it had been.
In the firſt experiment of this kind I uſed minium,
out of which all its air had been expelled by heat,
and which is of a yellow colour. In this proceſs ir
became whiter, and adhered a little to the glaſs.
When I ſcraped it off, I could not be quite ſure that
any part of it was become real lead; but it evidently
approached towards a metallic ſtate, by being of a
more compact texture than before.
In this ſtate of the experiments I communicated
the reſult of my obſervations to my friend Mr.
Bewly, who ſuggeſted to me, that, probably, it was
the
1
240
Part II.
OBSERVATIONS ON
the lead in the glaſs tubes that had attracted the
phlogiſton; and I preſently found this to be the
caſe. For when I had filled a green glaſs tube with
the inflammable air, and fealed it hermetically, as I
had done the fint glaſs tubes, I expoſed it to a melt-
ing heat, which is greater than that which fint glaſs
will bear, without producing any change of colour
in it. What remained of the air in the tube, that
did not eſcape when part of it was melted, was ſtill
ſtrongly inflammable.
It
appears, therefore, from this experiment, that
the calx of lead, in the form of glaſs, has a ſtronger
affinity with phlogiſton than any thing in the com-
poſition of inflammable air, in a degree of heat cap-
able of melting glaſs. Or, if there be no proper
conſtituent part of inflammable air beſides phlogiſton,
the attraction of the calx is ſo great, as to reduce the
phlogiſton from an elaſtic and uncombined ſtate to
a fixed and combined one.
Having, by means of theſe glaſs tubes, effected a
complete decompoſition of inflammable air, the
phlogiſton in it having united with the glaſs of the
lead; I thought that, if there had been any acid in
its compoſition, it would then be diſengaged, and be
found in the tube. In order to find whether there
was any acid in it, or not, I poured into one of theſe
tubes a ſmall quantity of water made blue with the
juice of turnfole; but it came out as blue as it went
ins
SEC,
SET: III.
242
INFLAMMABLE AIR
!
SECTION III.
Of ſulphurated inflammable Air.
HERE is no kind of air whichi admits ſuch
a variety of modifications as the inflammable;
nor ſhall we think this extraordinary, when we con-
fider that phlogiſton, which is the diſtinguiſhing in-
gredient in it, enters into a greater variety of combi-
nations with ſolid ſubſtances than perhaps any other
principle in nature, and is the cauſe of a greater va-
riety of properties in them. Spirit of wine, oil, ful-
phurcharcoal, and metals, are ſubſtances as different
from each other, both in their external appearance,
their degrees of conſiſtence; and other chemical
properties; as any things in nature, and yet the
principal ingredient in them all is the ſame phlo-
giſton, as may be proved by the actual transferring
of it from any one to any other of them. Inflam-
mable air likewiſe extracted from each of theſe ſub-
ſtances, as alſo that from putrid vegetables, and by
other proceſſes, of which an account has been given
in the preceding ſections, are all remarkably different,
and appear to be fo, as we ſhall preſently ſee, when
they are decompoſed. I ſhall now give an account
VOL. I.
R
of
242
Part II.
OBSERVATIONS ON
of another ſpecies of this kind of air, which I
term fulphurated, from the ſtrong ſmell that it has
of ſulphur, or rather liver of ſulphur, and its be-
ing loaded with a greater quantity of matter ; which,
though at the firſt black, yet on expoſure to the
air preſently affumes a yellowiſh colour. I ſhall
recite the experiments in which I obſerved this
peculiar ſpecies of air; in the order in which I
made them, noting the other appearances that -aċ-
companied them, though they have not any im-
mediate relation to the air of which I am treating.
When I was engaged in that courſe of experi-
ments in which ſteam, and the vapour of various
fuid ſubſtances, was brought into contact with
folid ſubſtances red hot, I treated manganeſe in
this manner, and eſpecially a quantity with which
Mr. Woulfe, had formerly furniſhed me, which
was not in powder, but in a large maſs, juſt as
it is dug out of the earth. A few ounces of this
I put into an earthen tube, open at both ends.
But cloſing one of them with a cork, while the
middle part of the tube was red hot, and the
other orifice was furniſhed with an apparatus pro-
per for collecting the air that might be expelled
from it, I received forty ounce meaſures of air,
of which one ſixth was fixed air, and the reſt of
the ſtandard of 1.7, lambently inflammable. Nó
more air coming in this diſpoſition of the apparatus,
I opened
1
1
Ser. III. İNFLAMMABLE AIR.
243
I opened the other end of the tube, and with a
proper contrivance for the purpoſe, fent through
it a. quantity of ſteam; in which circumſtances
air was produced more copiouſly than before. Of
this I received about fifty ounce meaſures, ob-
ſerving that one ſeventh of it was fixed air, and
the reſt of the ſtandard of 1.8, not lambently, but
explofively; infiammable. The laſt portions of
this air were very turbid, and the ſmell of the
air, and eſpecially that of the laſt portion; was
very ſulphureous, and; I obſerved, tinged the water
of a very dark colour, by depoſiting in it a quan-
tity of blackiſh matter. However, the air itſelf
became preſently tranſparent; and had no other
appearance than that of any other kind of air;
when I left in my trough a jar filled with it.
Having been intent on ſome other experiments;
I was ſurpriſed to find, on looking on the jar
about ten minutes afterwards, that it was quite
black, ſo that I could ſee nothing in the inſide of
it. In order to obſerve how it came to be fo, I
afterwards filled another jar with this kind of air,
and obſerved that when the water was well ſub-
ſided, black ſpecks began to appear in different
places, and, extending themſelves in all directions,
at length joined each other, till the whole jar was
perfectly black, and the glais quite opake. When
this was done, I transferred the air to another
clean
R2
244
Part II.
OBSERVATIONS ON
clean jar, and it ſoon produced the ſame effect
upon this, though it never became ſo black as
the jar in which it had been firſt received. It
alſo frequently happened that only the lower part
of the jar would become black, as if this matter,
with which it was toaded, had kept ſubſiding,
though inviſibly, in the maſs of air, and occupied
the lower regions of it only, leaving the upper
part entirely free from it. When the veſſels thus
tinged black were expoſed to the open air, that
colour preſently diſappeared, and a yellow or brown
incruſtation was left upon it.
Thinking, from this circumſtance, that this black
coating conſiſted of fome volatile phlogiſtic matter,
I placed the jars which had this black tinge with
their mouths inverted in veffels of water, in order
to obſerve the effect which the change of colour
might have on the common air contained in them,
In theſe circumſtances the black tinge prefently
went off, and was ſucceeded by the yellow colour,
but without producing any ſenſible change in the
air. In ſome caſes, however, I thought that it
was injured; but it was by no means ſo much fo
as I had expected. After depoſiting this black
matter, the air ftill retained its ſulphureous ſmell,
and as far as I can judge, will never entirely
leave it.
It
1
f
SeEt. III.
245
INFLAMMABLE
AIR
It is by no means the univerſal property of
manganeſe to yield this fulphurated inflammable
air, but inuſt have been owing to ſomething pecu-
liar to this ſpecimen, and perhaps to ſomething
accidentally mixed with it. For when I repeated
the experiment with other manganeſe, which I
had from a glaſs houſe, in which it is uſed, I had
no fuch appearance. From four ounces of this
manganeſe, treated as the preceding, I got without
ſteam, 256 ounce meaſures of air, of which about
one tenth was fixed air. Then ſending ſteam over
it, I got more air, but in no great quantity, about
ten ounce meaſures in an hour; though probably
much more might have been procured, if the
proceſs had been continued. This was dephlo-
giſticated; for, mixed with two equal meaſures
of nitrous air, the ſtandard was 0.28, which ſhews
that it was exceedingly pure. But one tenth of
this was fixed air, as in the former portion, which
agrees with the experiments I formerly made with
this ſubſtance when I found that heat alone would
expel from it a quantity of very pure air,
The next time that I got this fulphurated in-
flammable air, was as unexpected as the preceding;
and this experiment was the firſt thing that gave
me any inſight into the nature of it. Having
occaſion to make a large quantity of inflammable
air, inſtead of freſh turnings of iron, I happened
R3
to
>
246 OBSERVATIONS ON:
Part II
to take ſome, parts of which had been heated by
a burning lens in vitriolic acid air, in which, as I
have obſerved, it melts with great readineſs, and
gathers into balls. When this iron was diffolved
in diluted oil of vitriol, though there were only a
fèw pieces in the quantity that I uſed which had
been melted in this manner, the water in which
the air was received was very black, and depoſited
more ſediment than in the experiment with the
manganeſe. The jars alſo which contained it
were preſently as black as ink, but became yellow
when expoſed to the open air. This inflammable
air had alſo the fame offenſive fulphureous ſmell;
ſo that there could be no doubt of its being the
ſame kind of air which I had got from Mr:
Woulfe's manganeſe. There was in it, however,
a 'mixture of vitriolic acid air, as I perceived
when I burned a large quantity of it in a glaſs
þalloon, in order to collect the water that might
be produced in this proceſs. All the inſide of the
balloon was filled with a denſe white cloud, all
the time that the air was burning in it, and the
water produced was very ſenſibly acid. In reality,
the ſame effects were produced as if ſulphur had
been burned in the veſſel,
As I had no doubt, but that the iron which
had been melted in vitriolic acid air was the fame
as what is called ſulphurated iron, or iron with which
I
ſulphur
+
Sez. III.
247
INFLAMMABLE AIR.
ſulphur is incorporated, I now completely aſcer-
tained it by making a quantity of ſulphurated iron,
dipping it when red hot into melted ſulphur.
This iron, treated as the other had been, yielded
exactly ſuch air as I have been deſcribing, ſo
that I could have no doubt with reſpect to the real
origin of it
When I decompoſed this air, by firing it with
an equal quantity of dephlogiſticated air, the dimi-
nution of bulk was the ſame as when I uſed the
common inflainmable air, ſo that it did not appear
to contain either more or leſs phlogiſton; buț
there was a ſmall quantity of fixed air produced,
which is never the caſe with inflammable air pro-
cured with oil of vitriol, though it is ſometimes
when it is procured froin iron with ſpirit of ſalt.
When the ſulphurated inflammable air is received
in veſſels containing mercury, there is very little
black matter depoſited from it; but it appears
when it is transferred into yeffels containing
water.
Though jars thinly coated with this black mata
ter become yellow when expoſed to the open air,
this is not the caſe with that which is collected
from the water in which the air has been confined.
For when the water is evaporated from it, it ad-
heres to the evaporating veſſel in the form of a
perfectly black incruſtation. This ſubſtance, though
RA
is
248
OBSERVATIONS ON: Part ITA
it does not burn blue on a hot iron, yet-fhews
evident ſigns of containing fulphur. For when
the nitrous acid has taken from it its ſuperfluous
phlogiſton, it has both the colour and the ſmell
of ſulphur.
SECTION
IV.
Metals, and other Subſtances containing Phlogiſton,
formed by imbibing inflammable Air.
+
1
TH
HERE are few ſubjects, perhaps none, that
have occaſioned more perplexity to chemiſts,
than that of phlogiſton, or, as it is ſometimes called,
the principle of inflammability. It was the great
diſcovery of Stahl, that this principle, whatever
it be, is transferable from one ſubſtance to another,
how different foever in their other properties,
ſuch as ſulphur, wood, and all the metals, and
therefore is the ſame thing in them all
. But
what has given an air of myſtery to this ſubject,
has been that it was imagined, that this principle,
or ſubſtance, could not be exhibited except in com-
bination with other ſubſtances, and could not be
made
Seet. IV
249
INFLAMMABLE AIR.
made to aſſume ſeparately either a fuid or ſolid
form. It was alſo aſſerted by fome, that phlogiſton
was ſo far from adding to the weight of bodies,
that the addition of it made them really lighter
than they were before; on which account they
choſe to call it the principle of levity. This opinion
had great patrons.
Of late it has been the opinion of many cele-
brated chemiſts, Mr. Lavoiſier among others,
that the whole doctrine of phlogiſton is found-
ed on miſtake, and that in all caſes in which
it was thought that bodies parted with the prin-
ciple of phlogiſton, they in fact loft nothing; but
on the contrary acquired ſomething; and. in moſt
caſes an addition of ſome kind of air; that a
metal, for inſtance, was not a combination of two
things, viz. an çarth and phlogiſton, but was pro-
bably a ſimple ſubſtance in its metallic ſtate; and
that the calx is produced not by the loſs of phlo-
giſton, or of any thing elſe, but by the acquiſition
of air.
The arguments in favour of this opinion, eſpe-
cially thoſe which are drawn from the experiments
that Mr. Lavoiſier made on mercury, are ſo ſpe-
cious, that I own I was - myſelf much inclined
My friend Mr. Kirwan, indeed,
always held that phlogiſton was the ſame thing
with inflammable air. I did not, however, accede
1
r
to adopt it.
to
!
250
OBSERVATIONS ON Part II.
T
1
to it till I thought I had diſcovered. it by direct
experiments, made with general and indeterminate
views, in order to aſcertain ſomething concerning
a ſubject which had given myſelf and others ſo
much trouble,
I began with repeating the experiments in which
I had found that inflammable air, made red hot
in fint glaſs tubes, gave them a black tinge, and
was in a great meaſure abſorbed, which I diſ-
covered to be owing to the cals of lead in the
glaſs, attracting phlogiſton from the inflammable
air.
I found, however, great difficulty in repeating
theſe experiments; and the quantity of inflamma-
ble air operated upon in them, is neceſſarily ſo
ſmall, that the reſult is always. liable to much
uncertainty. I thought, therefore, that throwing
the focus of a burning lens upon a quantity of
pounded Aint glaſs, ſurrounded witli inflammable
air, or rather on the calx of lead alone, in the
fame circumſtances, would be a much eaſier ex-
periment, and might bring me nearer to my
object; and on making the experiment it imme.
diately anſwered far beyond my expectation,
For this purpoſe, I put upon a piece of a
broken crucible (which could yield no air) a
quantity of minium, out of which all air had been
extracted; and placing it upon a convenient ſtand,
intro-
Set. IV.
25T
INFLAMMABLE AIR.
1
introduced it into a large receiver, filled with in-
flammable air, confined by water.
As ſoon as
the minium was dry, by means of the heat thrown
upon it, I obſerved that it became black, and
then ran in the form of perfect lead, at the fame
time that the air diminiſhed at a great rate, the
water aſcending within the receiver. I viewed
this proceſs with the moſt eager and pleaſing ex-
pectation of the reſult, having at that time no
fixed opinion on the ſubject; and therefore I could
not tell, except by actual trial, whether the air
was decompoſing in the proceſs, ſo that ſome
other kind of air would be left, or whether it
would be abſorbed in toto. The former I thought
the more probable, as, if there was any ſuch
thing as phlogiſton, inflammable air, I imagined,
conſiſted of it, and ſomething elſe. However, I
was then fatisfied that it would be in my power
to determine, in a very ſatisfactory manner, whe-
ther the phlogiſton in inflammable air had any
baſe or not, and if it had, what that baſe was.
For ſeeing the metal to be actually revived, and
that in a conſiderable quantity, at the ſame time
that the air was diminiſhed, I could not doubt,
but that the calx was actually imbibing ſomething
from the air; and from its effects in making the
calx into metal, it could be no other than that to
which
1
1
¢
4
1
'252 OBSERVATIONS ON Part II.
which chemiſts had unanimouſly given the name
of phlogiſton.
Before this firſt experiment was concluded, I
perceived, that if the phlogiſton in inflammable
air had any baſe, it muſt be very inconſiderable:
for the proceſs went on till there was no more
room to operate without endangering the receiver 3
and examining, with much anxiety, the air that
remained, I found that it could not be diſtinguiſh-
ed from that in which I began the experiment,
which was air extracted from iron by oil of vitriol,
I was, therefore, pretty well fatisfied that this in-
flammable air could not contain any thing be-
fides phlogiſton; for at that time I reduced about
forty five ounce meaſures of the air to five.
In order to aſcertain a fact of ſuch importance
with the greateſt care, I afterwards carefully expell-
ed from a quantity of minium all the phlogiſton, and
every thing elſe that could have aſſumed the form
of air, by giving it a red heat when mixed with ſpirit
of nitre; and immediately uſing it in the manner
mentioned above, I reduced a hundred and one
ounce meaſures of inflammable air to two. To judge
of its degree of inflammability, I preſented the flame
of a ſmall candle to the mouth of a phial filled with
it, and obſerved, that it made thirteen ſeparate ex-
ploſions, though weak ones (ſtopping the mouth of
the
.
1
L
Sect. IV.
253
INFLAMMABLE AIR.
1
the phial with my finger after each exploſion) when
freſh made inflammable air, in the fame circum-
ſtances, made only fourteen exploſions, though
ſtronger ones.
After this experiment I could not heſitate to con-
clude ", that this inflammable air went totally, and
without decompoſition, into the lead which I form-
ed at that time, and if the neceſſary circumſtances
of the experiment be conſidered, it will be thought
extraordinary that, even admitting this, the reſult
ſhould be ſo deciſively clear in favour of it: for, in
the firſt place, the greateſt care muſt be uſed to ex-
pel all air from the minium, and it muſt be uſed
before it can have attracted any from the atmoſphere;
and in the next place, the water alſo (a conſiderable
quantity of which muſt be ufed, and which will alſo
be heated in the proceſs) ſhould be made as free
from air as poſſible. In theſe circumſtances, had I
found the ſmall reſiduum, of two ounce meaſures
from a hundred and one, to have been phlogiſticai-
ed or fixed air, I ſhould not have been diſappoint-
ed, and it would not have prevented my conclud-
* In this concluſion, I overlooked one obvious conſideration, viz.
that water, or any thing ſoluble in water, might be the baſis of
inflammable air. All that could be abſolutely inferred from the
experiment was, that this baſis could not be any thing that was
capable of ſubſiſting in the form of air. It will be ſeen, that I
afterwards made the experiment with the air confined by mer-
cury.
ing
254
OBSERVATIONS ON Part ft.
$
ز
ing that phlogiſton was the ſame thing with inflam-
mable air, contained in a combined ſtate in metals,
juſt as fixed air is contained in chalk and other cal-
careous ſubſtances; both being equally capable of
being expelled again in the form of air.
Afterwards, uſing a calx of lead, which had been
prepared in the ſame manner with the former, but
which had remained for ſome weeks expoſed to the
air, I found, that when by uſing it I had reduced
150 ounce meaſures of inflammable air to ten, this
reſiduum was phlogiſticated air. . But examining
this calx ſeparately, I found that it gave, by heat in
a glaſs veffel, a conſiderable quantity of phlogiſticat-
ed air.
I muſt obferve, that the minium ſhould not be
reduced to a perfectly compact glaſs of lead; for theri
it will be too refractory to be eaſily revived by
this proceſs. Making uſe of ſome of it; I found
that I could only melt it;, but that a copious black
fume came from it, and coated the inſide of the re-
ceiver: an experiment which I ſhall repeat and re-
conſider. I muſt alſo obſerve, that the lead which
I procured in the above mentioned proceſs was not
to be diſtinguiſhed from any other lead, and that the
inflammable air was all procured from iron by oil of
vitriol.
When I made uſe of inflammable air from wood,
I found, that though I was able to reduce minium
with
Sect. IV.
255
INFLAMMABLE AIR.
with it, it was effected with more time and difficulty.
Forty ounce meaſures of this kind of inflammable
air I reduced to twenty five; after which I found that
the heat of the lens produced only glaſs of lead, and
-no metal. The air was ſtill, however, inflammable;
and there was a ſmall mixture of fixed air in it. This
kind of inflammable air, which burns with a lam-
bent flame, I have ſome reaſon to think, conſiſts
of an intimate.union of fixed air with that which is
of the exploſive Kind extracted from metals. The
reſult of thoſe experiments which I made with that
kind of inflammable air which is collected in the
proceſs for making phoſphorus, and which burns
with a lambent yellow flame, was ſimilar to thoſe
which I made with inflammable air from wood,
which burns with a lambent white flame.
Having had this remarkable reſult with in-
fiammable air, I immediately tried all the other
kinds of air in the ſame manner; but in none of
them did I procure any thing from the minium
beſides glaſs of lead, except in alkaline air, and
vitriolic acid air. In fixed air, nitrous air, phlo-
giſticated air, marine acid air, fluor acid air, as
allo in common and dephlogiſticated air, I got
no metal at all. In vitriolic acid air there was
but a ſmall quantity of lead produced, and I have
obſerved that this kind of air imparts a certain
portion of phlogiſton to common air (or rather in-
1
bibes
256
Part II.
OBSERVATIONS ON
bibes a part of the dephlogiſticated air from it) rén-
dering the remainder in ſome meaſure phlogiſti-
cated, though by no means in fo great a degree
as nitrous air
Though nitrous air and phlogiſticated air cer-
tainly contain phlogiſton, they appear by theſe
experiments to hold it too obſtinately to part with
it to minium in this proceſs, notwithſtanding nitrous
air quits it ſo readily to reſpirable air. I would ob-
ferve, that there were fome peculiar appearances in
the experiments I made to revive the calx of lead
in theſe kinds of air in which the attempt did not
ſucceed; but I muſt repeat the experiments, and
note the appearances more accurately, before I res
port them.
In alkaline air lead ſeems to be formed from the
minium as readily as in inflammable air; and indeed I
thought rather more fo; and this is a remarkable
confirmation and illuſtration of thoſe experiments;
in which, by taking the electric ſpark in a quan-
tity of alkaline air, I converted it into three times
as much pure inflammable air ; an experiment
which, on account of the extraordinary nature of
it, I have repeated many times ſince I firſt pub-
liſhed the account of it, and always with the ſame
reſult.
This experiment alſo throws ſome light upon
thoſe in which, by expoſing iron to nitrous air,
.
I pro
Sext. IV.
257
INFLAMMABLE AIR.
1
I produced a ſtrong ſmell of volatile alkali;
an experiment which I have alſo frequently re-
peated with the ſame reſult. The reviving of
lead in alkaline air may alſo help us to conceive
how all acids ſhould have an affinity both to phlo-
gifton and to alkalies, which have hitherto appeared
to be things ſo very different from each other ;
ſince, from theſe experiments, it is probable that
one of them is fome modification of the other, or
a combination of ſomething elſe with the other.
To trace the connexion between the alkaline and
inflammable principles, is a curious ſubject; and
from theſe hints it may, perhaps, not be very
difficult to profecute it to advantage. It is evident,
however, from the following experiinents, that al-
kaline air is the compound, and inflammable air,
or phlogiſton, the more ſimple ſubſtance of the
two.
From five ounce meaſures and a half of alka-
line air I got, by means of litharge, ſeventeen
grains of lead, beſides fome that was diffolved in
the mercury, by which the air was confined.
There remained two ounce meaſures and a half,
which appeared to be phlogiſticated air, and to
have no fixed air in it. At another time, in eight
ounce meaſures of alkaline air I got fifteen grains
of lead, beſides what was diſſolved in the mercury,
which ſeemed to be a good deal in proportion to
VOL. I.
S
it.
+
1
1
1
258
OBSERVATIONS ON Part II.
it. There remained in this proceſs three ounce
meaſures and a half of phlogiſticated air, without
any mixture of fixed air in it.
Having thus produced lead in inffammable air,
I proceeded in my attempts to revive other metals
from their calces by the ſame means; and I fuc-
ceeded very well with tin, biſmuth, and ſilver;
tolerably well with copper, iron, and regulus of
cobalt; but not at all with regulus of antimony,
regulus of arſenic, zinc, or the metal of manga-
neſe.
I was deſirous alfo of aſcertaining by this means
the quantity of phlogiſton that enters into the com-
poſition of the ſeveral metals; but in this I found
more difficulty than I had expected; and this
aroſe chiefly from the allowance that was to be
made for the inflammable air which entered into
that
part
of the calx which was only partially re-
vived; and it was not eaſy to revive the whole of
any quantity of calx completely.
After many trials, I think I may venture to
ſay, that an ounce of lead abſorbs a hundred ounce
meaſures of inflammable air, or perhaps ſome-
thing more ; for in one reſult it ſeemed to have
imbibed in the proportion of 108 ounce mea-
ſures.
An ounce of tin abſorbs infanmable air in the
proportion of 377 ounce meaſures to the ounce.
An
SeEt. IV.
259
INFLAMMABLE AIR.
1
+
.
An ounce of copper from verditer abſorbed 403
ounce meaſures; from a ſolution of blue vitriol,
precipitated by ſalt of tartar, and afterwards made
red hot with ſpirit of nitre, 640; but from blue
vitriol itſelf gog ounce meaſures.
In this caſe,
however, much of the inflammable air went to
the formation of the vitriolic acid air, the ſinell
of which was very perceivable in the courſe of
the experiment. The copper that I made in this
way was brittle, and therefore ſeemed not to be
perfectly metallized; but being fuſed with borax,
it became perfect copper, and, as I think, with-
out any loſs of weight.
Biſmuth abſorbed inflammable air in the pro-
portion of 185 ounce meaſures to the ounce. The
calx I uſed was a precipitate from the ſolution of
this metal in ſpirit of nitre.
Iron I got from a precipitate of a ſolution of
green vitriol by ſalt of tartar, moiſtened with ſpirit
of nitre, and expoſed to a red heat. This cals
abſorbed in the proportion of 890 ounce meaſures
of the inflammable air to an ounce of iron, which
was in the form of a black powder ; but to all
appearance as much attracted by the magnet as
iron filings. But it could not be expected, that
perfect iron, containing its full proportion of phlo-
giſton, ſhould be produced in this manner, ſince
S2
in-
!
.
sho
OBSERVATIONS ON
Part II
inflammable air may be expelled from perfect iron
in this very proceſs
Silver I evidently revived from a ſolution of it
in ſpirit of nitre precipitated by falt of tartar, and
alſo from luna cornea. A quantity of this laſt ſub-
ſtance abſorbed twenty three ounce meaſures of
inflammable air; but I could not get any calx of
ſilver free from:ſmall grains of the perfect metal,
which was eaſily diſcovered by a magnifier, and
therefore I could not aſcertain the quantity of in-
fiammable air abſorbed by it.
Small grains of regulus of cobalt I produced
from zaffre, and inflammable air was abſorbed;
but I did not eſtimate the quantity.
A quantity of manganeſe abſorbed ſeven ounce
meaſures of inflammable air; but I could not per-
ceive any thing in it which had the appearance of
metal. But I imagined I had not heat enough
.for the purpoſe; and mixing with it ſome calcined
borax, I repeated the experiment, when there was
again an evident abforption of air, and in the
courſe of that experiment, I once thought that I
did perceive a ſmall globule of meer
Zinc and arſenic were only ſublimed in this pro-
ceſs. The ſame was the caſe with the glaſs of
* I have fince found that inflammable air cannot be expelled
from iron by heat, without ſome moiſture, which therefore ſeems
neceſſary to its conftitution.
antimony;
SET. IV.
261
INFLAMMABLE AIR.
antimony; but the experiment was attended with
this peculiar circumſtance, that when the glafs was.
melted in inflammable air, it formed itſelf into
needle-like cryſtals, arranged in a very curious
manner; and I could not produce that
appearance
in other kinds of air.
Inflammable air being clearly imbibed by the
calces of metals, and thereby reviving them, is a
ſufficient proof of its containing what has been
called phlogiſton ; and its being abſorbed by them
in toto, without decompoſition, is a proof that, ex-
cluſive of water, it is nothing beſides phlogiſton in
the form of rir, unleſs there ſhould be ſomething
folid depoſited from it at the ſame time that the
proper phlogiſtic part of it is abſorbed. With
reſpect to this, I can only ſay that, in the courſe
of the experiments, I did not perceive any thing
of the kind : for though in ſome of the proceſſes
there was a black ſmoke produced, in others I
could perceive nothing but part of the caix ſub-
liming, and clouding the glaſs. On this account,
however, I could not pretend to aſcertain the
weight of the inflammable air in the calx, ſo as to
prove that it had acquired an addition of weight
by being metalized, which I often attempted. But
were it poſſible to procure a perfect calx, no part
pf which ſhould be ſublimed and diſperſed, by the
heat neceſſary to be made uſe of in the proceſs, I
S3
ſhould
#
262
OBSERVATIONS ON Part II.
ſhould not doubt but that the quantity of inflam-
mable air imbibed by it would ſufficiently add to
its weight.
Beſides the formation of metals from their calces,
I had other proofs, and of a nature fufficiently
curious, of inflammable air containing phlogiſton.
Thus, by means of it, I was able to make phof-
phorus, nitrous air, liver of ſulphur, and fulphur it-
felf, in all of which phlogiſton is acknowledged to
be a principal ingredient.
Throwing the focus of the lens upon a quantity
of that glaſly matter which is made from calcined
bones by oil of vitriol in inflammable ait, ſome of
it was abſorbed, and all the inſide of the receiver
was covered with an orange coloured ſubſtance,
which had a ſtrong ſmell of phoſphorus. I then
wanted fun-fhine to continue the experiment; but
I was ſatisfied that there was ſufficient proof of
phoſphorus being actually formed in this manner.
With alkaline air I ſucceeded much better.
In two ounce meaſures and a half of this air, I
produced, from the glaſly matter mentioned above,
two grains of phoſphorus in one maſs, the veſſel
being only filled with white fuſes during the pro-
ceſs. One fourth of the bulk of the air remained,
and this was infiammable, burning with a yellow
lambent flame, exactly like that which is produced
in the proceſs for making phoſphorus.
4
That
Sect. IV.
263
INFLAMMABLE AIR.
!
That nitrous air contains phlogiſton is ſufficiently
evident, if there be any ſuch thing as phlogiſton:
and I have farther proved, that it contains very
nearly as much phlogiſton, in proportion to its
bulk, as inflammable air itſelf. I had now, how-
ever, the farther ſatisfaction to be able to make
nitrous air from its two conſtituent principles, viz.
nitrous vapour and inflammable air. The nioſt
eaſy proceſs for this purpoſe is, to throw a ſtream
of nitrous vapour into a large phial previouſly
filled with inflammable air. In this manner nitrous
air is inſtantly formed, and in great quantities;
but as this nitrous vapour is produced by the rapid
folution of biſmuth in ſpirit of nitre, which at the
ſame time produces a quantity of nitrous air, the
experiment is not quite unexceptionable. I there-
fore attempted the ſame thing in the following
manner.
Taking a quantity of what I have called a
nitrated calx of lead, which I firſt produced by
uniting nitrous vapour to minium (in conſequence
of which, from being a red and powdery ſubſtance,
it becomes white, compact, and brittle) I placed it
upon a ſtand, in a receiver filled with inflammable
air, and throwing the focus of the lens upon it,
there was a diminution of the inflammable air,
which amounted to about two thirds of the whole,
and during this time lead was revived from the
calx.
S4
264
Part II,
OBSERVATIONS ON
calx. After this there was no more diminution of
the air, or revival of the calx: and then examin-
ing what remained of the air, I found it to be all
ſtrongly nitrous: and, from the circumſtances in
which it was produced, it muſt have been form-
ed from the nitrous vapour contained in the calx,
and the inflammable air in the receiver. In or-
der to aſcertain the purity of this nitrous air, I
mixed it with an equal quantity of common air,
and found that they occupied the ſpace of 1.32
meaſures. Freſh nitrous air made in the uſual
way, and mixed with common air in the ſame
proportion, occupied the ſpace of 1.26. This
difference aroſe not from any impurity in the
nitrous air, but from the mixture of the dephlo-
giſticated air, which is alſo expelled from this calx
T
by heat.
Liver of ſulphur was procured by throwing the
focus of the lens upon vitriolated tartar in in-
flammable air, and it appeared to be perfectly
well formed.
Laſtly, to produce fulphur, I threw the focus
of the lens on a quantity of oil of vitriol, con-
tained in an hollow earthen veſſel, and evaporated
it to dryneſs in a receiver filled with infiammable
air; in conſequence of which the inſide of the
receiver acquired a whitiſh incruſtation, which
when warmed had a ſtrong ſmell of fulphur; and
repeating
+
SeEt. IV.
INFLAMMABLE AIR.
265
1
repeating the proceſs in the ſame receiver, I was
able, this ſecond time, to ſcrape off enough of
the matter to put on a piece of hot iron, and to
produce the genuine blue flame, as well as the
peculiar ſmell, of ſulphur,
7
1
1
1
PART
266
Part III.
OBSERVATIONS ON:
:
P A R T III. .
OF THE CONSTITUTION OF INFLAMMABLE AIR.
SECTION
I.
Experiments which prove that Water is a neceſary in-
gredient in inflammable Air.
firſt
any
part of inflammable air, and it may be worth
while to recite the experiments which led to that con-
clufion. Having put a quantity of iron-filings, care-
fully forted with a magnet, into one of the glaſs-veſ-
fels, fig. a, Pl. iv. I filled the reſt of the veſſel with
quickſilver; and placing it inverted in a baſon of
quickſilver, I threw the focus of the lens upon the
iron-filings, and preſently air was produced; which,
being examined, appeared to be inflammable, though
not
+
1
12
INFLAMMABLE AIR.
i
Sext. T.
267
not very ſtrongly fo. It reſembled inflammable air
that had been waſhed in water till its inflammability
was nearly gone. I alſo could not diſtinguiſh the
colour of the fame, when I made the exploſion in
the uſual manner, by the approach of a candle. Af-
ter the operation, the iron from which the air had
been extracted, had an exceedingly ſtrong ſmell,
exactly like that of very ſtrong inflammable air pro-
cured from metals by acids.
In the ſame manner I got air from the filings of
watch-ſprings which are made of the beſt of ſteel
and it was not to be diſtinguiſhed from the inflam-
mable air of the laſt experiment. Theſe filings, as
well as thoſe of iron, I had carefully forted with a
magnet, ſo that I believe there was no foreign mat-
ter mixed with them.
N. B. The ſpot on which the focus of the lens
was thrown, was much blacker than any other part
of the filings; and during the application of the
heat, a quantity of the filings would ſometimes be
diſperſed, as by an exploſion below the furface of
them; owing, I ſuppoſe, to the ſudden generation
of air from ſome of the filings that lay under the
but where the heat could reach them.
Having thus got air from iron, I proceeded to
make ſimilar experiments on other '
metals. But as
all the other metals have more or leſs affinity with
quickſilver, I was obliged to have recourſe to a
vaciluliil;
+
268 OBSERVATIONS ON
Part IIT.
vacuum. But being poſſeſſed of Mr. Smeaton's air-
pump, I could depend upon the vacuum being very
exact; ſo that very little common air could be mixed
with the air produced. That the filings of the
different metals might be perfectly unmixed, I pro-
cured new files, quite clean, and uſed one ſide of
each for each of the metals.
With this apparatus, I threw the focus of my lens
upon filings of zinc, and preſently got from them
air which was very ſtrongly inflammable. Zinc is
faid to contain more phlogiſton than the other me-
tals, and the difference between the inflammable air
from zinc, and that which I got from iron, was very
ſtriking
From braſs-duft I got inflammable air in confi.
derable plenty, and alſo from tin; but this laſt was
very ſlightly inflammable. I could not have
per-
ceived it to be fo at all but by dipping a lighted can-
dle into a veſſel full of it; whereas, in other caſes, I
made the trials by preſenting the flame of a candle
to the narrow mouth of a phial filled with the air.
That braſs ſhould yield inflammable air, I attribute
to the zinc, by the addition of which, copper is con-
verted into braſs.
Thus all the metals that yield inflammable air,
when diſſolved in acids, gave inflammable air alſo by
heat only. With other metals I had no ſucceſs.
Regulus of Antimony, heated in vacilo, ſmoked very
much,
Seet. T.
INFLAMMABLE AIR.
269
1
much, and blackened all the inſide of my receiver ;
but the air that I got from it was very little indeed,
and extinguiſhed a candle.
From biſmuth, and nickel, I got hardly any air at
all; but in theſe experiments the heat was not ad-
vantageouſly applied, and the biſmuth foon melted
into large lumps, on which my lens had no power.
I got no air from lead or copper. By throwing
the focus of the lens upon the former, the receiver
was filled with fumes; but the heat was by no means
fufficient for the experiment with copper.
It is generally faid, that charcoal is indeſtructible,
except by a red heat in contact with air. But I
found that it is perfectly deſtructible, or decompoſed,
in vacuo, or as will appear hereafter, by means of
water which it attracts when red hot from the mois-
ture in the receiver. For in theſe circumſtances,
and by the heat of a burning lens it is almoſt wholly
converted into inflammable air; ſo that nothing re-
mains beſides an exceedingly ſmall quantity of
white aſhes, which are ſeldom viſible, except when,
in very ſmall particles, they happen to croſs the fun-
beam, as they fly about within the receiver. It
would be impoſſible to collect or weigh them; but,
according to appearance, the aſhes thus produced
from many pounds of wood, could not be ſuppoſed
to weigh a grain. The great weight of aſhes pro-
duced by burning wood in the open air, ariſes from
5
what
+
270
Part III
OBSERVATIONS ON
+
what is attracted by them from the air. The air
which I get in this manner is wholly inflammable,
without the leaſt particle of fixed air in it. But, in
order to this, the charcoal muſt be perfectly well
made, or with ſuch a heat as would expel all the
fixed air which the wood contains; and it inult be
continued till it yield inflammable air only, which,
in an earthen retort, is foon produced.
Wood, or charcoal, is even perfectly deſtructible,
that is, reſolvable into inflammable air, in a good
earthen retort, and a fire that would about melt iron.
In theſe circumſtances, after all the fixed air had
come over, I have ſeveral times continued the
pro-
.ceſs during a whole day, in all which time inflam-
mable air has been produced equably, and without any
appearance of a termination. Nor did I wonder
at this, after ſeeing it wholly vaniſh into inflammable
air in vacuo. A quantity of charcoal made from
oak, and weighing about an ounce, generally gave
me about five ounce meaſures of infiammable air in
twelve minutes.
That water in great quantities is ſometimes pro-
duced from burning inflammable and dephlogiſti-
cated air ſeemed to be evident from the experiments
of Mr. Cavendiſh and Mr. Lavoiſier. I have alſo
frequently collected conſiderable quantities of water
in this way, though never quite ſo much as the
weight of the two kinds of air decompoſed. My
apparatus,
i
inta
in
SEET. T.
INFLAMMABLE AIR.
271
apparatus for this purpoſe was the following. Into
the mouth of a large glaſs balloon (a) Fig. 4. Pl. vii.
I introduced a tube from the orifice of which there
continually iſſued infiammable air, from a veſſel
containing iron and oil of vitriol.
This being
lighted, continued to burn like a candle. Pre-
fently after the lighting of it, the inſide of the bal-
loon always became cloudy, and the moiſture foon
gathered in drops, and ſettled in the lower part of the
balloon. To catch what might iſſue in the form of
vapour, in the current of air through the balloon,
I placed the glaſs tube (6) in which I always found
fome water condenſed. It is very poſſible, how
ever, that in both theſe modes of experimenting, the
water may be converted into a kind of vapour,
which is very different from ſteam, and capable of
being conveyed a great way through air, or even wa-
ter, without condenſation, along with the air with
which it is mixed; and on this account it may not
be poſſible, in either of theſe modes of experiment-
ing, to collect all the water which the two kinds
of air will yield. The nature of this kind of
vapour into which water may be changed, and
which is not readily condenſed by cold, is very
little
underſtood, but well deſerves the particular atten-
tion of philoſophers*. Even mercury will evapo-
.
Mr. Saullure has made fome valuable obfervations on this
ſubject.
rate,
MT
272,
OBSERVATIONS ON Part III
1
rate, ſo as to loſe weight, in a degree of heat below
that of boiling water.
That the water collected in the balloon.came from
the decompoſition of the air, and not from the freſh
air circulated through it, was evident from placing
balls of hot iron in the place of the fame, and find-
ing that, though the balloon was as much heated by
them as by the flame of the burning of the inflam-
mable air, and conſequently there muſt have been
the fame current of the external air through it, no
moiſture was found in the balloon.
When, in this manner, I burned inflammable air
from pure iron, the water I collected was as far as
I could perceive free from acid, and the inſide of the
balloon was quite clear, but when I uſed fulphorated
iron, there was a denſe white cloud that filled the in-
ſide of the balloon. There was alſo a ſtrong ſmell
of vitriolic acid air, and the water collected was fen-
fibly acid to the taſte.
Afterward, ſeeing much water produced in ſome
experiments in which inflammable air was decom-
poſed, I was particularly led to reflect on the relation
which they bore to each other, and eſpecially Mr.
Cavendiſh's ideas on the ſubject. He had told me
that notwithſtanding my former experiments, from
which I had concluded that inflammable air was
pure phlogiſton, he was perſuaded that water was ef-
ſential to the production of it, and even entered into
it
Sect. 1.
273
INFLAMMABLE AIR.
1
A
i
it as a conſtituent principle. At that time I did
not perceive the force of the arguments which he
ſtated to me, eſpecially as, in the experiments with
charcoal, I totally diſperſed any quantity of it with a
burning lens in vacuo, and thereby filled my receiver
with nothing but inflammable air. I had no fufpi-
cion that the wet leather on which my receiver ſtood
could have any influence in the caſe, while the piece
of charcoal was ſubject to the intenſe heat of the
lens, and placed ſeveral inches above the leather: I
had alſo procured inflammable air from charcoal in a
glazed earthen retort two whole days ſucceſſively, in
which it had given inflammable air without inter-
miſſion. Alſo iron filings in a gun-barrel, and a
gun-barrel itſelf, had always given inflammable air
whenever I tried the experiment.
Theſe circumſtances, however, deceived me, and
perhaps would have deceived any other perſon; for
I did not know, and could not have believed, the
powerful attraction that charcoal, or iron, appear to
have for water when they are intenſely hot. They
will find, and attract it, in the midſt of the hotteſt
fire, and through any pores that may be left open
in a retort; and iron filings are feldom ſo dry as not
to have moiſture enough adhering to them, capable
of enabling them to give a conſiderable quantity of
inflammable air. But my attention being now fully
awake to the ſubject, I preſently found that the cir-
· VOL. I.
T
cumſtances
274
OBSERVATIONS ON
Part III,
cumſtances above-mentioned had actually miſled me;
I mean with reſpect to the conclufion which I drew
from the experiments, and not with reſpect to the
experiments themſelves; every one of which, Į
doubt not, will be found to anſwer, whenever they
are tried by perſons of fufficient, ſkill and properly
attentive to all the circumſtances.
Being thus apprized of the influence of
unpera
ceived moiſture in the production of inflammable
air, and willing to aſcertain it to my perfect fatisfac-
țicn, I began with filling a gun-barrel with iron fil-
ings in their common ſtate, without taking any par-
ticular precaution to dry them, and I found that
they gave air as they had been uſed to do, and con-
tinued to do ſo many hours. I even got ten ounce
meaſures of inflammable air from two qunces of
iron filings in a coated glaſs retort. At length, how-
ever, the production of inflammable air from the
gun-barrel ceaſed; but on putting water into it, the
air was produced again, and a few repetitions of the
experiment fully ſatisfied me that I had been too pre-
cipitate in concluding that inflammable air is pure
phlogiſton.
I then repeated the experiment with the charcoal,
making the receiver the ſtand on which I placed the
charcoal, and the charcoal itſelf, as dry and as hot as
poſſible, and uſing cement inſtead of a wec leather to
exclude the air, In theſe circumſtances I was not
able,
.
1
Sect. 1.
275
IN FLAMMABLE AIR
able, with the advantage of a good ſun, and an ex-
cellent burning lens, to decompoſe quite ſo much as
two grains of the piece of charcoal, which gave me
ten ounce meaſures of inflammable air; and this f
imagine, was effected by means of ſo much moiſture
as was depoſited from the air in its ſtate of rarefac-
tion, and before it could be drawn from the re-
ceiver. To the production of this kind of inflam-
mable air I was therefore now convinced, that wau
ter is as neceſſary as to that from iron.
As inflammable air was produced in ſome expe .
riments; in which I endeavoured to change the na-
cure of water, by making it red hot in a gun-barrel,
the orifice of which was welded up, it may not be
improper juſt to mention them in this place, as they
ſhew the uſe of water in procuring this kind of air.
They will likewiſe ſerve to ſhew the expanſive force
of water in that ſtate. The experiments were made
in March 178:3.
Putting fixteen grains of water into a gun-barrel,
containing four ounce meaſures and a half, I got
it
welded up; and making it red hot, it burſt in the
middle after a few minutes. I aſcertained the
quantity of water, by putting it into a ſmall glaſs
tube, which I ſealed herinetically, and put within
the gun-barrel.
I then put ſix grains of water into the thicker
half of a muſket barrel, and three grains and a half
TO
into
376
OBSERVATIONS ON }
+
Part IIT
into a thinner barrel. Theſe did not 'burſt when
they were red hot, and being pierced under water,
inflammable air ruſhed out. I I repeated theſe expe-
riments, and always had the ſame reſult; inflam-
mable air being procured, when the gun-barrels
were opened under water ; and if the water was in
ſufficient quantity, part of it at leaſt (for I could not
meaſure it with exactneſs) was found in the barrel.
If inflammable air always contains water, water
ſhould be found whenever this kind of air is decom-
poſed; yet in heating red precipitate in inflammable
air, 1 at one time found little or no water. But having
uſed more precautions, I have ſince found it inſufficient
quantity in this proceſs, even though the inflammable
air was previouſly well dried with fixed ammoniac.
In this experiment I diſcontinued the proceſs after
three ounce meaſures of air were abſorbed, leaving
room in the veſſel, that the moiſture might be more
eaſily collected. With this precaution, and warming
the veſſel, I collected between an half and three-
fourths of a grain of water.
*This experiment may be thought to be favour-
able to the hypotheſis of water being compoſed of
fixed and inflammable air; as all water was care-
fully excluded, and yet a ſufficient quantity was
found in the proceſs. But beſides taking into the
account the water that is neceſſary to conſtitute the
inflammable air, why may not red precipitate, in its
drieſt
Sect. I.
277
INFLAMMABLE
AIR.
drieſt ſtate, be ſuppoſed to contain water, as well as
the ſcales of iron, which will bear any degree of hear
without parting with it. Red precipitate is made by
a liquid proceſs, and therefore the water, that may
enter into its compoſition as a calx, may quit ít
when it becomes a metal.
Having found that water is an eſſential ingredient
in the conſtitution of inflammable air, at leaſt as
produced from iron, it ſtill remained to be deter-
mined whether, when a calx is revived, and the
metal formed, the pure phlogiſton only entered the
calx, or, together with it, that water which was
neceſſary to its form of inflammable air.
In order to aſcertain this, I frequently revived
dry calces of lead in dry inflammable air, and exa-
mined the appearances of moiſture afterwards. But
notwithſtanding all the attention that I gave to the
proceſs, I could not be abſolutely certain, whether
more moiſture was left in the veſſel than might have
exiſted extraneouſly in the inflammable air, or whe-
ther, when the phlogiſton was abſorbed, it left be-
hind it any water that had been eſſential to it, as
inflammable air. Appearances were ſuch as foine-
times inclined me to think that every thing which
conſtitutes inflammable air goes into a calx, in order
to form the metal; ſo that if this, though a com-
pound thing, be called phlogiſton, it will ſtill be
true that phlogiſton and inflammable air are the ſame
thing; but, on the whole, I rather think that the
water
T3
1
278
Part III
OBSERVATIONS
ON
:
+
water which was eſſential to the conſtitution of inn
hammable air was left behind.
That water, however, may exiſt in bodies in a
combined ſtate, without appearing to be water, we
know in many caſes; but it is in nothing more evi.
dent than in the ſcales of iron, than which no ſub-
ſtance can have leſs the appearance of containing water,
But not to give a mere opinion, I ſhall recite
the particulars of a few experiments, which I made
with the view above-mentioned.
In fix ounce
meaſures and a half of inflammable air from iron,
I reviyed lead till it was reduced to one ounce mea-
fure and a half, care having been taken to make
every thing as dry as poſſible. Some moiſture,
howeyer, dịd appear, perhaps more than half a
grain ; but as this air had been confined by water,
ịt was no more than might have been contained in
it as an extraneous ſubſtance, It ought alſo to be
conſidered, that it mụſt be exceedingly difficult to
expel all moiſture by mere heat from ſuch a powe
dery ſubſtance as the yellow calx of lead, without
reviving the metal. All chemiſts well know how
firmly moiſture adheres to many ſubſtances, with
which it does not properly unite, and how much
heat is neceſſary to ſeparate them.
Again, in ſix ounce meaſures and a half of in-
flammable air from iron, I revived lead till there
remained 0.9 of a meaſure, and there was hardly
any more moiſture than I had reaſon to think might
have
J
1
1
Sect. I.
279
INFLAMMABLE AIR.
have been in the veſſel, independently of what was
contained in the inflammable air; and in order to
enable myſelf to judge of this, I melted an equal
quantity of the ſame minium, under a dry glaſs veſ-
fel with common air, when a little moiſture ap-
peared on the inſide of the glaſs, about as much, I
thought (for I could only judge by my eye) as
when I had revived the lead from that minium in
inflammable air. The quantity of lead revived was
only fixteen grains, but a good deal of the miniun
had been made black in the proceſs.
Laſtly, I expoſed ſome calx of lead to the heat of
the lens in inflammable air, received immediately
from the veſſel in which it was generated from iron
and oil of vitriol, becauſe this contains leſs water
than that which has been received in water and con-
fined by it ; and when ſix or ſeven ounce meaſures
of the air were abſorbed, I could not ſuppoſe, from
the appearance, that the water could be more than
a quarter of a grain. However, when I repeated
the experiment once more, I thought there might
be about half a grain of water, which is more than
I can well account for, without ſuppoſing that the
water which was neceſſary to the conſtitution of in-
Hammable air, and which I ſuppoſe to be about
half its weight, was left behind when the pure phlo-
giſton revived the calx. This, therefore, is the
opinion
I 4
780
Part III.
OBSERVATIONS
ON
opinion to which I am inclined; ſo that I do not think
that any water enters into the conſtitution of any of
the metals.
SECTION II.
Inflammable Air from Charcoal and Iron, &c. by
Means of Steam*,
EY
VER ſince the diſcovery of the diminution of
reſpirable air in thoſe proceſſes which are ge-
nerally called phlogiſtic, it has been a great object
with philoſophers to find what becomes of the air
which difappears in them,
Mr. Cavendiſh was of opinion, that when air is
decompoſed, water only is produced ; and Mr.
Watt concluded from ſome experiments, of which
I
gave an account to the Royal Society, and alſo
This ſection (which was an article in the Philofophical Trani
actions, Vol. 75, p.279) might have beenintroduced into Part I. which
treats of the production of inflammable air; but as it likewiſe
proves the compoſition of it from water and phlogiſton, it will,
upon the whole, ftand better in this connexion,
from
1
Sect. II.
281
INFLAMMABLE AIR.
from fome obſervations of his own, that water con-
ſiſts of dephlogiſticated and inflammable air, in
which Mr. Cavendiſh and M. Lavoiſier concur
with him; but Mr. Lavoiſier is well known to
maintain, that there is no ſuch thing as what has
been called phlogiſton; affirming inflammable air to
be nothing elſe but one of the elements or conſti-
tuent
parts
of water.
Such were the hypotheſes to which I had a view,
when I began the following courſe of experiments,
which I hope will be an admonition to myſelf,
as well as to others, to adhere as rigorouſly as
poſſible to aftual obſervations, and to be extremely
careful not to overlook any circumſtance that may
poſſibly contribute to any particular reſult. I ſhall
have occaſion to notice my own miſtakes with re-
ſpect to concluſions, though all the facts were ſtrictly
as I have repreſented them. But whilſt philofo-
phers are faithful narrators of what they obſerve,
no perſon can juſtly complain of being miſled by
them; for to reaſon from the facts with which
they are ſupplied, is no more the province of the
perſon who diſcovers them, than of him to whom
they are diſcovered.
I had tranſmitted the vapour of ſeveral Auid
ſubſtances through red hot earthen tubes, and there-
by procured different kinds of air. M. Lavoiſier
adopted the ſame proceſs, but uſed an iron tube;
and
"
1
282
Part 211.
OBSERVATIONS ON
and by means of that circumſtance made a very
valuable diſcovery which had eſcaped me.
I had
indeed, on one occaſion made uſe of an iron tube,
and tranſmitted. fteam through it; but not having
at that time any view to the production of air, I
did not collect it at all, contenting myſelf with
obſerving that water, after being made red hot,
was ſtill water, there being no change in its ſenſible
properties. Being now farther inſtructed by the
experiment of M. Lavoiſier, I was determined to
repeat the proceſs with all the attention I could
give to it; but I ſhould not have done this with
ſo much advantage, if I had not had the aſſiſtance
of Mr. Watt, who always thought that M. Lavoi-
ſier's experiments by no means favoured the con-
cluſion that he drew from them. As to myſelf,
I was a long time of opinion that his concluſion
was juſt, and that the inflammable air was really
furniſhed by the water being decompoſed in the
proceſs. But though I continued to be of this
opinion for ſome time, the frequent repetition of
the experiments, with the light which Mr. Wate's
obſervations threw upon them, ſatisfied me at
length that the inflammable air came from the
charcoal, or the iron.
I ſhall firſt relate the reſult of the experiments
that was made with charcoal, and then thoſe with
iron and other ſubſtances, in contact with which
(when
+
Sect. II
283
INFLAMMABLE AIR
(when they were in a ſtate of fuſion, or at leaſt
red hot) I made ſteam, or the vapour of other
liquid ſubſtances, to paſs. I ſhall only obſerve
that, previous to this, I began to make the experi-
ments with coated glaſs tubes, which I found to
anſwer very well during the proceſs, though they
never failed to break in cooling. At length I pro-
cured a tube of copper, on which, as M. Lavoiſier
diſcovered, ſteam had no effect; and at laſt I made
uſe of earthen tubes, with which Mr. Wedgwood,
that moſt generous promoter of ſcience, liberally
ſupplied me for the purpoſe ; and thefe, glazed
on the outſide only, I find far preferable to
copper.
The diſpoſition of the apparatus, with which
theſe experiments were made, was as follows. The
water was made to boil in a glaſs retort, which
communicated with the copper or earthen tube
that contained the charcoal or iron, &c. and which,
being placed in an horizontal poſition, was fur-
rounded with hot coals. The end of this tube
oppoſite to the retort communicated with the pipe
of a common worm tub, ſuch as is generally uſed
in diſtillations, by means of which all the ſuper-
fluous ſteam was condenſed, and collected in a
proper receptacle, while the air which had been
produced, and had come along with it through
the worm tub, was tranſmitted into a trough of
water,
1
284
Part III.
OBSERVATIONS
ON
water, where proper veſſels were placed to receive
it, and aſcertain the quantity of it; after which I
could examine the quality of it at leiſure*.
In the experiment with charcoal, I found un-
expected difficulties, and conſiderable variations in
the reſult; the proportion between the charcoal
and water expended, and alſo 'between each of
them and the air produced, not being ſo nearly
the ſame as I imagined they would have been.
Alſo the quantity of fixed air that was mixed with
the inflammable air varied very much. This
laſt circumſtance, however; ſome of my experi-
ments may ſerve to explain. Whenever I had
no more water than was fufficient for the produc-
tion of the air, there was never any ſenſible quan-
tity of uncombined fixed air mixed with the in-
flammable air from charcoal. This was particu-
larly the caſe when I produced the air by means
of a burning lens in an exhauſted receiver, and
alſo in an earthen retort with the application of
an intenſe heat. I therefore preſume, that when
the ſteam tranſmitted through the hot tube con-
taining the charcoal was very copious, the fixed
air in the produce was greater than it would
otherwiſe have been: The extremes that I have
obſerved in the proportion of the fixed to the in-
The diſpoſition of this apparatus may be ſeen Pl. VII. fig. 2ę
flammable
SET. IT.
285
INFI
INFLAMMABLE AIR.
flammable air have been from one twelfth to
one fifth of the whole. As I generally produced
this air, the latter was the uſual proportion; and
this was excluſive of the fixed air that was inti-
mately combined with the inflammable air, and
which could not be ſeparated from it except by
decompoſition with dephlogiſticated air; and this
combined fixed air I ſometimes found to be one
third of the whole maſs, though at other times not
quite ſo much.
To aſcertain this, I mixed one meaſure of
this inflammable air from charcoal (after the un-
combined fixed air had been ſeparated from it by
lime water) with one meaſure of dephlogiſticated
air, and then fired them by the electric ſpark. Af-
ter this I always found that the air which remained
made lime water very turbid, and the proportion
in which it was now diminiſhed, by waſhing in
lime water, ſhewed the quantity of 'fixed air that
had been combined with the inflammable. That
the fixed air is not gererated in this proceſs, is
evident from there being no fixed air found after
the exploſion of dephlogiſticated air and inflam-
mable air from iron *.
* When I wrote this paper, I imagined that the fixed air,
which was found on the decompoſition of this inflammable air
with dephlogiſticated air, had been contained in the inflammable
air. But it will appear, that it muſt have been formed by the
anion
V
1
286
Part III.
OBSERVATIONS ON
Notwithſtanding the above-mentioned variations,
the loſs of weight in the charcoal was always much
exceeded by the weight of the water expended;
which was generally more than double that of the
charcoal; and this water was intimately combined
with the air; for when I received a portion of it
in mercury, no water was ever depoſited from it.
The experiment which, upon the whole, gave
me the moſt ſatisfaction, and the particulars of
which I ſhall therefore recite, was the following:
Expending ninety four grains of perfect charcoal
(by which I mean charcoal made with a very
ſtrong heat, ſo as to expel all fixed air from it)
and 240 grains of water, I procured 840 ounce
meaſures of air, one fifth of which was fixed air,
and of the inflammable part nearly one third inord
appeared to be fixed air by decompoſition..
Receiving this kind of air in a variety of ex-
periments, but not in the preceding ones in par-
ticular (for then I could not have aſcertained the
quantity of it) conſiſting of fixed and inflammable
air together, I found ſome variations in its ſpecific
gravity, owing, I imagine, to the different propor-
tions of fixed air contained in it; but upon the
whole, I think, that the proportion of fourteen
union of phlogiſton (or inflammable air) and dephlogiſticated air,
made by the exploſion; though it is remarkable that no fixed air
is formed when the inflammable air from iron is uſed.
grains
Seet. II.
INFLAMMABLE AIR.
287
grains to forty ounce meaſures is pretty near the
truth, when the proportion of fixed air is about
one fifth of the whole. With reſpect to the weight
of the inflammable air after the fixed air was ſe-
parated from it, I found no great difference, and
think it may be eſtimated at eight grains to thirty
punce meaſures.
Upon theſe principles, the whole weight of the
840 ounce meaſures of air will be 294 grains
that of the charcoal will be
that of the water
94
240
3:34 which, con
ſidering the nature of the experiment, will perhaps
bé thought to be tolerably near to that of the air.
If the air be analyzed, the 840 ounce meaſures.
will be found to contain
168 of uncombined fixed air=151 grains.
add 672 impure inflammable
179
Jo that the whole
330
840 will weigh
It may, however, be ſafely concluded from this
experiment, and indeed from every other that I
made with charcoal, that there was no more pure
inflammable air produced than the charcoal itſelf
may be very well ſuppoſed to have ſupplied.
There is, therefore, no reaſon for deſerting the
old eſtabliſhed hypotheſis of phlogiſtou on account
of
4
288
Part Iit.
OBSERVATIONS ON
of theſe experiments, ſince the fact is by no means
inconſiſtent with it. The pure inflammable air,
with the water neceſſarily contained in it, would
weigh no more than about thirty grains, while the
loſs of weight in the charcoal was ninety four
grains. But to this muſt be added the phlogiſton
contained in 392 ounce meaſures of fixed air,
which, according to Mr. Kirwan’s proportion, will
be nearly fixty five grains, and this and the thirty
grains will be ninety five grains.
The baſis to this fixed air, as well as to the in-
flammable, muſt have been furniſhed by the water;
and I afterwards found that water is about one
half of the weight of fixed air. '
Before I conclude my account of the experi-
ments with charcoal, I would obſerve, that there
is another on which I place ſome dependence, in
which, with the loſs of 178 grains of charcoal,
and 528 grains of water, I procured 1410 ounce
meaſures of air, of which the laſt portion (for I
did not examine the reſt) contained one fixth part
of uncombined fixed air. This was made in an
earthen tube glazed on the outſide.
The experiments with iron were more ſatisfac-
tory than thoſe with charcoal, being ſubject to leſs
variation; and they by no means require us to
ſuppoſe that the inflammable air comes from the
water, but only from the iron, as the quantity of
water
5
i
:
1
11
Sect. II. INFLAMMÅBLE AIR. 289
water expended, deducting the weight of the air
produced, was as nearly as could be expected in
experiments of this kind, found in the addition of
weight gained by the iron. And though the in-
flammable air procured in this proceſs is between
one third and one half more than can be procured
from iron by a folution in acids, the reaſon may
be, that much phlogiſton is retained in the folu-
tions, and therefore much more may be expelled
from iron, when pure water, without any acid,
takes the place of it. I would farther obſerve,
that the produce of air, and alſo the addition of
weight gained by the iron, are much more eaſily
aſcertained in theſe experiments than the quantity
of water expended in them, on account of the great
length of the veſſels uſed in the proceſs, and the
different quantities that may perhaps be retained
in the worm of the tub; though I did not fail to
uſe all the precautions that I could think of, to
guard againſt any variation on theſe accounts.
Of the many experiments which I made with
iron, I ſhall content myſelf with reciting the fol-
lowing reſults. With the addition of 267 grains
to a quantity of iron, and the loſs of 336 grains
of water, I procured 840 ounce meaſures of in-
flammable air ; and with the addition of 140 grains
to another quantity of iron, and the conſumption
VOL. I.
U
of
290
OBSERVATIONS ON Part III.
of 254 grains of water, I got 420 ounce meaſures
of air*.
The inflammable air produced in this manner
is of the lighteſt kind, and free from that very
offenſive ſmell which is generally occaſioned by the
rapid ſolution of metals in oil of vitriol, and it is
extricated in as little time in this way as it is pof-
ſible to do it by any mode of ſolution. On this
account it occurred to me, that it muſt be by
much the cheapeſt method that has yet been uſed
of filling balloons with the lighteſt inflammable air.
For this purpoſe it will be proper to make uſe of
caſt iron cylinders of a conſiderable length, and
about three or four inches, or perhaps more, in
diameter. Though the iron tube itſelf will con-
tribute to the production of air, and therefore may
+
* If the perfect accuracy of the former of theſe experiments
may be depended on (and it may always be preſumed, that thoſe
in which little water is expended are preferable to thoſe in which
more is conſumed) the water that neceſſarily enters into this kind
of inflammable air is about equal in weight to the phlogiſton that
is in it.
The water expended was 336 grains, and the iron gained 267
grains. Suppoſing it to have loſt phlogiſton equal to half the
weight of the inflammable air, viz. 840 ounce meaſures =25 graine
(the whole weight of that air being so grains) the water that really
entered into the iron muſt be eſtimated at 292 grains (which is
#67 of 25). This deducted from 336, leaves. a remainder of 34,
which is not much more than 257 or half the weight of the in
flammable air.
become
SEEL. IT:
291
INFLAMMABLE AIR.
.it
1
become unfit for the purpoſe in time; yet, for
any thing that I know to the contrary, the ſame
tube may ſerve for a very great number of pro-
ceſſes, and perhaps the change made in the inſide
ſurface may protect it from any farther action of
the water, if the tube be of ſufficient thickneſs;
but this can only be determined by experiment.
Having recommended this proceſs as the cheap-
eſt and the moſt convenient for filling balloons, ;
eſpecially when tubes of caſt iron ſhould be made
uſe of; I was willing to make a trial of one, in
order to form fome judgment how long they
would laſt for the purpoſe. I therefore procured
one of an inch and a quarter in diameter, and not
more than a quarter of an inch in the thickneſs of
the metal ; and making the middle part of it red
hot, ſent ſteam through it; and from the reſult of
four or five proceſſes with the ſame tube, I have
little doubt, but that, if they were made of the
thickneſs of half an inch in the metal, and care
was taken to coat them on the outſide with clay
and ſand, the ſame tube might probably ſerve
tweñty times. That the reader may form fome
judginent as well as myſelf, I ſhall mention the
reſult of my obſervations,
I heated the tube four or five different times,
and in each proceſs tranſmitted as much water
through it as would have been more than fufficient
U2
to
+
292
Part III.
*OBSERVATIONS ON
1
1
to decompoſe all the iron that it could have con-
tained. At firſt four ounce meaſures of water
procured 180 ounce meaſures of inflammable air,
and then fix ounce meaſures procured only 160
ounce meaſures. I then examined the tube, and
found that when both the inſide and outſide were
well fcraped with a ſharp inſtrument, it had loft
twenty five grains in weight. The ſcales from
the outſide weighed 282 grains, while all that I
could
get
from the inſide weighed only thirty fix
grains. Conſequently the tube had gained in
weight 283 grains. After this I heated it again,
and tranſmitted through it fix more ounces of
water; which yielded only ſixty ounce meaſures
of air.
From theſe experiments it may be inferred,
that the tube would ſoon have ceaſed to give any
air; the inſide being changed to fome depth by
the action of the ſteam, and yet it was not much
diſpoſed to exfoliate. In time it would, no doubt,
have become brittle, and might be in danger of
breaking, from its diſpoſition to bend in the courſe
of the proceſs. This bending was very conſider-
able; but did not ſeem to ariſe from any tendency
in the iron to melt. Perhaps by turning it in cool-
ing, this bending, and conſequently the danger of
cracking after much uſe, might be prevented; or
this property of bending might in a great meaſure
ceaſe,
Sect. II.
293
INFLAMMAPLE AIR.
1
ceaſe, when the metallic ſtate of the tube was de-
ſtroyed; and yet with care might continue a firm
and compact tube, and as fit for this proceſs as
at the firſt. If this ſhould be the caſe (which ex-
perience alone can determine) it is not to ſay how
long a tube of this kind might laft. It would
then be a kind of earthen tube, of the moſt perfect
nature, completely air tight, without being ſubject
to ruſt or decay.
Upon the whole, ſhould the fondneſs for bal-
loons be reſumed, I ſee no reaſon why far the
greateſt part of the expence attending the filling
of them might not be ſaved by means of this proceſs,
A complete apparatus for it would not coſt half fo
much as the filling of a ſingle balloon, that would
carry a man, in the common way, and would ſerve
at leaſt a conſiderable number of times, with the
expence of a very few pounds each time; as there
would be hardly any thing to pay for beſides fire
and attendance, for a few hours. For ſuch iron as
would beſt anſwer for this purpoſe might, in moſt
places, be had for a mere trifle.
One apparatus,
conveniently fixed, might ſerve for a whole town
or neighbourhood,
Some eſtimate of what may be expected from
this method of procuring inflammable air may be
formed from the following obfervations. About
twelve inches in length of a copper tube, three
fourths
1
U 3
U 3 v
:
1
OBSERVATIONS ON
Part III.
294
fourths of an inch in diameter, filled with iron turn-
ings (which are more convenient for this purpoſe
than iron filings, as they do not lie ſo cloſe, but
admit the ſteam to paſs through their interſtices)
when it was heated, and a ſufficient quantity of
ſteam paſſed through it, yielded thirty ounce mea-
ſures of air in fifty ſeconds; and eighteen inches
of another copper tube, an inch and a quarter in
diameter, filled and treated in the farne 'manner,
gave two hundred ounce meaſures in one minute
and twenty five ſeconds; ſo that this larger tube
gave air in proportion to its ſolid contents com-
pared with the ſmaller ; but to what extent this
might be depended upon I cannot tell. However,
as the heat penetrates ſo readily to ſome diſtance,
the rate of giving air will always be in a greater
proportion than that of the ſimple diameter of the
tube.
The following experiment was made with a view
to aſcertain the quantity of inflammable air that
may be procured in this way from any given quan-
tity of iron. Two ounces of iron, or 960 grains,
when diſſolved in acids, will yield about 800
ounce meaſures of air ; but treated in this man-
ner it yielded 1054 ounce meaſures, and then the
iron had gained 329 grains in weight, which
is little ſhort of one third of the weight of the
iron.
Con
1
+
Sect. II.
INFLAMMABLE AIR.
295
1
Conſidering how little this inflammable air
weighs, viz. the whole 1054 ounce meaſures not
more than ſixty three grains, and the difficulty of
aſcertaining the loſs of water to fo finall a quantity
as this, it is not poſſible to determine, from a pro-
ceſs of this kind, how much water enters into the
compoſition of the inflammable air of metals. It
would be more eaſy to determine this circum-
ſtance with reſpect to the inflamınable air of char-
coal, eſpecially by means of the experiment made
with a burning lens in vacuo. In this method
two grains of charcoal gave at a medium thirteen
ounce meaſures of inflammable air, which, in the
proportion of thirty ounce meaſures to eight grains,
will weigh 3.3 grains; ſo that water in the com-
poſition of this kind of inflammable air is in the
proportion of 1.3 to 2, thoụgh there will be ſome
difficulty with reſpect to the fixed air intimately
combined with this kind of inflammable air.
The cxperiments above-mentioned relating 10
iron were made with that kind which is malleable;
but I had the ſame reſult when I made uſe of
ſmall nails of caſt iron, except that theſe were
firmly faſtened together after the experiment, the
ſurfaces of them being cryſtallized, and the cryſ-
tals mixed with each other, ſo that it was with
great difficulty that they could be got out of the tube
after the experiment; and in general the ſolid parts
:
U 4
of
296
OBSERVATIONS ON
Part III.
+
of the nails were broken before they were ſeparated
from each other. Indeed the pieces of malleable
iron adhered together after the experiment, but by
no means fo firmly.
Caſt iron annealed (by being kept red-hot in
charcoal) is remarkably different from the caſt iron
which las not undergone that operations eſpecially
in its being, to an extraordinary degree, more fo-
luble in acids. With the turnings of annealed caſt
iron I made the following experiment. From 960
grains of this iron, and with the loſs of 480 grains
of water, I got 870 ounce meaſures of inflamma-
ble air, and tranſmitting ſteam through them a ſe-
cond times I got 150 ounce meaſures more. The
iron had then gained 246 grains in weight, and the
pieces adhered firmly together ; but being thin they
were eaſily broken and got out of the tube, whereas
it had required a long time, and a ſharp ſteel inſtru-
ment, to clear the tube of the caſt-iron nails.
Haying made another experiment with iron, with
as much attention as I could give to it, I ſhall in
the firſt place mention that. From two ounces of
įron turnings (which is caſt iron annealed) I got in
the firſt inſtance 985 ounce meaſures of air, with
the loſs of 528 grains of water ; and the iron, I
found, had gained 292 grains in weight. Then
making four ounces of water of this reſiduum paſs
over the fame iron, it gained four grains more, and
all
I
Sect. II. INFLAMMABLE AIR,
297
all the air that I procured was 998 ounce meaſures.
So that (as extreme accuracy is not to be obtained
in proceſſes of this kind) it may be ſaid that two
Ounces of this kind of iron will, in this way, yield
1000 ounce meaſures of air; whereas by ſolution
in vitriolic acid, it would have yielded about 800.
Conſequently more air by two fifths may be pro-
cured by this new mode of treatment, which alone
ſhould recommend it to thoſe who fill balloons.
Having procured water from the ſcales of iron
(by heating them in inflammable air) and having
thereby converted it into perfect iron again, I did
not entertain a doubt but that I ſhould be able to
produce the ſame effect by heating it with charcoal
in a retort; and I had likewiſe no doubt but that I
ſhould be able to extract the additional weight
which the iron had gained (viz. one-third of the
whole) in water. In the former of theſe con-
jectures. I was right; but with reſpect to the latter,
I was totally miſtaken.
Having made the ſcales of iron, and alſo the
powder of charcoal very hot, previous to the expe-
riment, ſo that I was ſatisfied that no air could be
extracted from either of them ſeparately by any de-
gree of heat, and having mixed them together
while they were hot, I put them into an earthen re-
tort, glazed within and without, which was quite
impervious to air. This I placed in a furnace, in
which
1
1
298 OBSERVATIONS ON Part IIT.
+
which I could give it a very ſtrong heat ; and con-
nected with it proper veſſels to condenſe and collect
the water which I expected to receive in the courſe
of the proceſs. But, to my great ſurpriſe, not one
particle of moiſture came over, but a prodigious
quantity of air, and the rapidity of its production
aſtoniſhed me; ſo that I had no doubt but that the
weight of the air would have been equal to the loſs
of weight both in the ſcales and in the charcoal ; and
when I examined the air, which I repeatedly did,
I found it to contain one-tenth of fixed air; and the
inflammable air, which remained when the fixed air
was ſeparated from it, was of a very remarkable
kind, being quite as heavy as common air. The
reaſon of this was ſufficiently apparent when it was
decompoſed by means of dephlogiſticated air ; for
the greateſt part of it was fixed air.
The theory of this proceſs I imagine to be, that
the phlogiſton from the charcoal reviving the iron,
the water with which it had been ſaturated, being
now ſet looſe, affected the hot charcoal as it would
have done if it had been applied to it in the form of
ſteam as in the preceding experiments; and therefore
the air produced in theſe two different modes have
a near reſemblance to each other, each containing
fixed air, both combined and uncombined, though
in different proportions; and in both the caſes I
found theſe proportions ſubject to variations, In
one
I
:
m
Sect. II.
INFLAMMABLE AIR.
299
1
one proceſs with charcoal and ſcales of iron, the firſt
produce contained one fifth of uncombined fixed
air, the middle part one tenth, and the laſt none at
all. But in all theſe caſes the proportion of com-
bined fixed air varied very little.
Why air and not water ſhould be produced in
this caſe, as well as in the preceding, when the iron
is equally revived in both, I do not pretend perfectly
to underſtand. There is, indeed, an obvious dif-
ference in the circumſtances of the two experiments ;
as in that with charcoal the phlogiſton is found in a
combined ſtate ; whereas in that of inflammable
air, it is looſe, or only united to water; and
and per-
haps future experiments may diſcover the operation
of this circumſtance*.
-
* This experiment ſeems to be deciſive againſt the hypotheſis of
Mr. Layoifier, and others, who ſay that the inflammable air pro-
cured by means of iron and charcoal, comes from the water, and
who think that by this means they can exclude phlogiſton. For,
according to them, neither the ſcales of iron, nor the charcoal,
contain phlogiſton, or any thing from which inflammable, air can
be made, but are merely ſubſtances capable of imbibing, pure air,
and thereby ſetting at liberty the inflammable air contained in the
water; ſuppoſing the ſcales of iron to have been only iron faturated.
with dęphlogiſticated air. But had this been the caſe, there was
nothing in either of the materials made uſe of in this experiment
from which the inflammable air could poflibly come, there being
no water contained in either of them. But fuppofing the reality of
phlogiſton, and its conſtituting a part of metals, of charcoal, and
of inflammable air, the experiment is very intelligiblc.
After
7.
i
300
Part III.
OBSERVATIONS ON
+
1
After having tranſmiitted ſteam in contact with
charcoal and iron in : copper tube, I propoſed to do.
the ſame with other ſubſtances containing phlogiſton,
and I began with bones, which were burned black,
and had been ſubjected to an intenſe heat, covered
with ſand, in an earthen retort. From three ounces
of bones thus prepared, and treated as I had done
the charcoal, I got 840 ounce meaſures of air, with
the loſs of 288 grains of water. The bones were
by this means made perfectly white, and had loſt
110 grains of their weight. As the air ceaſed to
come a conſiderable time before all the water had
been tranſmitted through the tube containing them,
I concluded that the air was formed from the phlo-
giſton contained in the bones, and ſo much water as
was neceſſary to give it the form of air.
This air differs conſiderably from any other kind
of inflammable air, being in ſeveral reſpects a me-
dium between that from charcoal and that from
.iron.. It contains about one fourth of its bulk of
uncombined fixed air, but not quite one tenth in-
' timately combined with the remainder. The wa-
ter that came over was blue, and pretty ſtrongly al-
kaline, which muſt have been occaſioned by the
volatile alkali not having been intirely expelled from
the bones in the former proceſs, and its having in
part diſſolved the copper of the tubc in which the
experiment was made.
I fub,
.
+
1
Sext. III.
301'
INFLAMMABLE AIR.
I ſubjected to the ſame proceſs a variety of ſub-
ſtances that are faid not to contain phlogiſton, but
I was never able to procure inflammable air by
means of them ; which ſtrengthens the hypotheſis of
the principal element in the conſtitution of this air
having been derived from the ſubſtance ſuppoſed to
contain phlogiſton, and therefore that phlogiſton is
a real ſubſtance, capable of aſſuming the form of
air by means of water and heat.
T
SECTION III.
Of the Aetion of Steam on various Subſtances in a
red Heat.
HAT
AVING procured inflaminable air by ſend-
ing ſteam over red hot iron, I afterwards ex-
tended the ſame proceſs to other ſubſtances, and as
moſt of thoſe contained phlogiſton, and yielded in-
flammable air, I ſhall recite them in this place.
Having been able to decompoſe iron by con-
verting it into ſcales, I alſo found that in this way,
I could readily procure flowers of zinc, as well as in-
flammable air from that metal. The flowers came
Qver
302
Part III.
OBSERVATIONS ON
1
over in a very attenuated ſtate, the air being loaded
with them. It might be poſſible, however, to con-
trive an apparatus to collect them.
Braſs being made with a mixture of zinc and
copper, and zinc being ſo eaſily decompoſed by
ſteam, whenever a copper tube is ordered for the
purpoſe of theſe experiments, particular care ſhould
be taken that there be no mixture of braſs in it,
though it is difficult to have copper caſt ſmooth and
ſolid without a mixture of either braſs or tin, which
is not much better. Even pure copper tubes be-
come brittle, and at length crack in theſe experi-
1
ments.
Having at one time been perſuaded to have a
little braſs inixed with the copper in one of theſe
tubes, I conſented that the ſmalleſt quantity that
could be ſuppoſed to be neceſſary to make the tube
compact, ſhould be put into it. But notwithſtand-
ing this, and though the tube had a quarter of an
inch thickneſs of metal, it fell to pieces in the very
firſt experiment, in which I fent the ſteam of no
more than two or three ounces of water through it.
Inflammable air was produced very copiouſly, and
the flowers of zinc were mixed with it; ſo readily
did the ſteam ſeparate the zinc from the copper,
though the heat was only fufficient to make the tube
red hot, and was far from melting it,
Lead
4
1
Seet, III.
303
INFLAMMABLE AIR.
Lead would probably be far leſs affected than cop-
per in theſe experiments ; but then it will not bear
a red heat without melting. I made the ſteam of
about four ounces of water paſs over four ounces of
melted lead, in an earthen tube, with hardly any
ſenſible effect. The loſs of water was not more
than 0.2 of an ounce meaſure.'
After uſing charcoal in the experiments recited in
the preceding ſection, I went through one proceſs
with coak, or the cinder of pit coal, and found that
from 174 grains of coak, and with the loſs of 528
grains of water, I got 1700 ounce meaſures of air,
of which one fifth was fixed air, and thirty ounce
meaſures of it weighed ten grains leſs than an equal
bulk of common air. The analyſis of this air will
be found in the ſection appropriated to that ſub-
ject.
On iron ore this proceſs had no effect. The ſame
was the caſe with the trial I made of quick lime, and
ſuch would probably be the caſe with dephlogiſti-
cated earths in general.
With manganeſe, however, the reſult was differ-
ent. Having made the ſteam of four ounces of
water paſs over 828 grains of this ſubſtance, which
had been expoſed to a ſtrong heat in an earthen re-
tort fome time before, I got thirty five ounce mea-
fures of air, almoſt the whole of which was pure
fixed air, with a reſiduum a little better than com-
+
mon
304
OBSERVATIONS ON
Part III.
I
mon air: The manganeſe had loſt 132 grains, and
from being black, was become very brown. Again,
I tranſmitted the ſteam of eight ounces of water
over two ounces and a half of manganeſe, and got
about 100 ounce meaſures of pure fixed air, with
a reſiduum a little phlogiſticated. The manganeſe
had loſt 112 grains.
1
S E C T I ON
IV.
Whether inflammable or nitrous Air contain nore
Pblogiſton.
r
+
T is well known that both nitrous and inflam-
IT
mable air contain phlogiſton, but in very dif-
ferent ſtates, becauſe their ſpecific gravities, and
other properties, are moſt remarkably, different:
Many ſchemes have occurred to me to aſcertain the
proportion of phlogiſton that each of them containss
and at length I thought of attempting the ſolution
of this problem, by burning inflammable air in a
given quantity of common air. For though in-
flammable air will not part with its phlogiſton to
common air when cold, it will, like other combuſ-
tible
Seet. IV.
305
INFLAMMABLE AIR.
1
tible ſubſtances, when heated to a certain degree.
It is then decompoſed, and the phlogiſton that en-
tered into its compoſition phlogiſticates the air in
which it is burned ; and the degree of phlogiſtica-
tion may be meaſured by the teſt of nitrous air. I,
thereforej proceeded as follows.
In an eight ounce phial, containing many nails;
and a quantity of water with oil of vitriol, I pro-
duced inflammable air ; and making it burn with
a ſmall fame, at the orifice of a glaſs tube through
which the air was tranſmitted (being cemented into
the cork of the phial) I covered the fame with a
receiver that contained twenty-one ounce meaſures
of air, ſtanding in water. After ſix minutes, the
flame went out ; when, immediately catching the
air that was produced in the next ſix minutes, and
alſo in the ſix minutes following, I concluded that
ſeven ounce meaſures had been produced, and de-
compoſed, during the ſix minutes in which it had
continued to burn.
Then examining the air in which it had burned,
I found it ſo far phlogiſticated, that equal meaſures
of it and of nitrous air occupied the ſpace of 1.65
meaſures; and common air mixed with one third
as much nitrous air, being again mixed in equal
proportions with the ſame freſh nitrous air, occu-
pied the ſpace of 1.68 meaſures. It appeared, there-
fore, that the twenty one ounce meaſures of air, having
VOL. I.
Х
received
r
!
1
306
OBSERVATIONS ON Part III.
received the phlogiſton of one third as much inflam-
mable air, viz. feven ounce meaſures, was about
as much phlogiſticated as it would have been with
a mixture of the ſame proportion of nitrous air.
Conſequently, equal meaſures of nitrous and in-
flammable air contain about equal quantities of
phlogiſton.
Of this curious problem, however, I have ob-
tained a more accurate ſolution from the mode of
experimenting introduced by that excellent philofo-
pher Mr. Volta ; who fires inflammable air in com-
mon air, by the electric ſpark, and conſequently
can determine the exact proportion of the inflamma-
ble air decompoſed in a given quantity of common
air. The reſult of this proceſs agreeing with that
of the former, leaves little doubt with reſpect to the
concluſion I have drawn from them.
Having prepared a ſtrong glaſs tube, in one end
of which I had cemented a piece of wire, I filled it
with water, and introduced into it another piece of
wire, ſo as to come within about half an inch of
the former wire, that an electric exploſion might
eaſily paſs between them.
Into this tube, thus prepared, I transferred, in
the firſt place, one meaſure of inflammable air, and
three of common air; and then, by means of an
electric exploſion between the wires, in the central
place of the air, I fired all the inflammable air,
which
1
Sect. IV.
307
INFLAMMABLE AIR.
which would then be decompoſed, and, of courſe,
part with its phlogiſton to the common air with
which it was mixed. After the exploſion, I ac-
cordingly found it to be completely phlogiſticated.
This alſo would have been the conſequence of mix-
ing the ſame proportion of nitrous air with the com-
mon air. But to determine the problem with ac-
curacy, it was neceſſary to uſe ſuch a proportion of
inflammable as would only phlogiſticate the common
air in part.
I therefore mixed one meaſure of inflammable
air with three meaſures of common air, and after the
exploſion found it to be ſo far phlogiſticated, that
one ineaſure of this and one of nitrous air occupied
the ſpace of 1.8 meaſures ; and this I alſo found,
by the ſame teſt, to be exactly the ſtate to which
a mixture of one meaſure of the fame nitrous air
brought three meaſures of the fame common air.
In order to obtain a farther confirmation of my
concluſion, I mixed one meaſure of inflammable
air with four meaſures of common air; and after
the exploſion I alſo found, by the teſt of nitrous
air, that it was phlogiſticated exactly as much as by
the mixture of an equal quantity of nitrous air. And
repeating the experiment with the ſame proportion
of inflammable and common air, I found that after
the exploſion the air was diminiſhed, without
mixing with nitrous air, juſt as much as one mea-
X2
fure
308
Part III.
OBSERVATIONS ON
ſure of nitrous air diminiſhed four meafures of com-
mon air, viz. from 7.4 to 5.2 meaſures.
Having ſince this given more attention to theſe
experiments, I have ſeen reaſon to conclude that
inflammable air from iron and water, contains more
phlogiſton than nitrous air, in the proportion of
ten to nine, For nine meaſures of inflammable air
will diminiſh dephlogiſticated air as much as ten of
nitrous air.
11
SECTION
V.
The Analyſis of different kinds of inflammable Air.
EFORE I proceed to the analyſis of the
different kinds of inflammable air, which is
the ſubject of this ſection, I ſhall obſerve, that the
pureſt we can procure (which is that from metals
by ſolution in the mineral acids, or rather that by
means of ſteam from red-hot iron) ſeems to confift
of phlogiſton and water, and that neither acid nor
alkali is a neceſſary ingredient in it; though, when
it
;
Seft. V.
309
INFLAMMABLE AIR.
1
1
it is produced by means of either of them, a ſmall
portion of either may be retained in it, as an ex-
traneous ſubſtance. That this, however, is the caſe,
has been very clearly ſhewn by Mr. Senebier,
though I think that the production of inflammable
air by means of iron and ſteam only, without either
acid or alkali, fufficiently proves that his hypotheſis
of inflammable air neceſſarily acquiring ſome faline
bafis, cannot be well founded.
It was, indeed, my own firſt opinion, that in-
flammable air conſiſts of acid and phlogiſton. Af-
terwards I adopted the opinion of Mr. Kirwan, viz.
that it is pure phlogiſton in the form of air, but
at preſent I am fully ſatisfied with the opinion of
Mr. Cavendiſh, that water is an eſſential ingre-
dient in the conſtitution of this kind of air.
That no acid is neceſſarily contained, or at leaſt
in any fenſible quantity, either in inflammable air,
though produced by means of acids, or in the de-
phlogiſticated air of the atmoſphere, ſeemed to be
evident from the following experiment, which I
made with the greateſt care.
Taking a baſon
which contained a ſmall quantity of water tinged
blue with the juice of tumſole, I placed in it a bent
tube of glaſs, which came from a veſſel containing
iron and diluted oil of vitriol; and lighting the cur-
rent of inflammable air, as it iſſued from this tube,
fo that it burned exactly like a candle, I placed over
4
I
X 3
it
310
Part III.
OBSERVATIONS ON
4
it an inverted glaſs jar; ſo that the mouth of it was
plunged in the liquor. Under this jar the inflam-
mable air burned as long as it could, and when it
was extinguiſhed, for want of more pure air, I ſuffered
the liquor to riſe as high as it could within the jar,
that it might imbibe whatever ſhould be depoſited
from the decompoſition of either of the two kinds
of air. I then took off the jar, changed the air in
it, and lighting the ſtream of inflammable air, re-
placed the jar as before. This I did till I had de-
compoſed a very great quantity of the two kinds of
air, without perceiving the leaſt change in the co-
lour of the liquor, which muſt, I thought, have
been the caſe if any acid had entered as a neceſſary
conſtituent part into either of the two kinds of air.
I alſo found no acid whatever in the water which
was procured by keeping a ſtream of inflammable
air conſtantly burning in a large glaſs balloon,
through which the air could circulate, ſo that the
flame did not go out.
With reſpect to inflammable air itſelf, I have be-
fore obſerved, that when ſufficient care is taken to
free it from any acid vapour that may be accidentally
contained in it, it is not in the ſmalleſt degree af-
fected by a mixture of alkaline air. On the whole,
therefore, I have at preſent no doubt but that pure
inflammable air, though it certainly contains water,
does not neceſſarily contain any acid. Yet an acid
vapour
1
.
+
Seet. V.
311
INFLAMMABLE AIR.
.
vapour may be eaſily diffuſed through it, and may
perhaps in many caſes be obſtinately retained by it,
as no kind of air ſeems to be capable of ſo great
a variety of impregnations as inflammable air is.
That there are different kinds of inflammable
air, has been obſerved by moſt perſons who have
made any experiments on air. That which has
been moſt commonly obſerved is, that ſome of
them burn with what may be called a lambent flame,
ſometimes blue, ſometimes yellow, and ſometimes
white, like the flame from wood or coals in a
common fire; whereas another kind always burns
with an exploſion, making more or leſs of a report,
when a lighted candle is dipped into a jar filled
with it. Of the latter kind is that which is ex-
tracted from metals by means of acids, &c. and
of the former kind is that which is expelled from
wood, coal, and other ſubſtances by heat. It has
alſo been obſerved, that theſe kinds of inflammable
air have different ſpecific gravities, the pureſt kind,
or that which is extracted from iron, &c. being
about ten times lighter than common air, buç
ſome of the other kinds not more than twice as
light.
The cauſe of this difference I once thought I
had diſcovered to be the heavier kinds of inflam,
mable air containing a proportion of fixed air, lo
intimately combined with them, ſo as not to be
dif
X 4
!
312
Part II
QBSERVATIONS ON:
*
diſcoverable by lime water, while the lighteſt kind
contained no fixed air at all. This hypotheſis I
formed from decompoſing them with common or
dephlogiſticated air, by the electric exploſion. For,
after the experiment with the heavier kinds of in-
fiammable air, I always found a quantity of fixed
air in the reſiduum, but none at all after the ex-
periment with the lighteſt kind.
· In order to decompoſe any kind of inflamma-
ble air, I generally mix it with an equal quantity
of dephlogiſticated air, and then confine them in
a ſtrong glaſs veſſel, previouſly filled either with
water or mercury, and I make an electric ſpark in
ſome part of the mixture, by means of wires in-
ſerted through the ſides of the veſſel, and nearly
meeting within it. By this proceſs, I imagined,
that I was able to aſcertain two things relating to
the conſtitution of different kinds of inflammable
air, viz. the quantity of combined fixed air (as I
then thought it to be) and likewiſe the relative
quantity of phlogiſton contained in cach of them.
The former appeared by waſhing the air with
lime water after the exploſion, and obſerving how
much of them was abſorbed, and the latter by
examining the reſiduum with the teſt of nitrous
air, and obſerving the purity of it. In moſt of
theſe experiments I made uſe of dephlogiſticated
air, in preference to common air, becauſe I could
not
+
Seet. V.
313
INFLAMMABLE AIR.
not make ſome kinds of inflammable air to ex-
plode at all with common air. Otherwiſe I ſhould
have preferred this, as being the moſt nearly of
the fame quality. However, I always noted the
degree of purity of the dephlogiſticated air that
I made uſe of before I began any of theſe analyſes.
Finding, however, that in ſome caſes more fixed
air was found after the exploſion of the two kinds
of air, than could poſſibly have been contained in
the inflammable air, on account of the weight of
it, I was ſatisfied that there muſt have been a real
generation of it, by an union of the inflammable
and dephlogiſticated air. It is remarkable, how-
ever, that ſome kinds of inflammable air ſhould .
ſo readily unite with dephlogiſticated air, ſo as to
make a conſiderable quantity of fixed air; and
that others, treated in the ſame manner, ſhould not
do this at all; and alſo that thoſe which do it
ſhould be the heavier kinds of inflammable air.
This is a new and curious ſubject of inveſtigation.
The pureſt and lighteſt inflammable air is that
which is extracted from iron, and other metals,
by a ſolution in the acids, or by means of ſteam.
One meaſure of this kind of air, and one of de-
phlogiſticated (ſuch as that, when mixed with two
equal quantities of nitrous air, there remained 0.72
of a meaſure) exploded together in the manner
deſcribed above, were reduced to 0.6 of a mea-
ſure,
1
314
Part II.
OBSERVATIONS ON
-
1
ſure, no fixed air was found in the reſiduum, and
when examined with an equal quantity of nitrous
air, was reduced to 0.87 of a meaſure.
With the ſame dephlogiſticated air I examined
inflammable air that had been got from a mixture
of finery cinder and charcoal, and found, that after
the exploſion, the two meaſures were reduced only
to 1.85, but that by waſhing in the lime water,
they were reduced to 1.2. Conſequently 0.65 of
a meaſure of fixed air had been generated in the
proceſs. When this was ſeparated from it, and
the remainder examined by nitrous air, it appeared
to be of the ſtandard of 0.9; ſo that the dephlogiſ.
ticated air had been more injured by this than
by an equal quantity of the common inflammable
air, though the difference in this reſpect was not
conſiderable.
In another proceſs with this kind of inflamma-
ble air, the diminution after the exploſion was to
1.55, and that after the waſhing in lime water to
0.65 of a meaſure; ſo that there had been a gene-
ration of o.9 of a meaſure of fixed air. In another
experiment the firſt diminution was to 1.6, and
the ſecond 0.66, ſo that 0.94 of a meaſure of fixed
air had been produced. And laſtly, in another
proceſs, the firſt diminution was to 1.6, and the
ſecond to 0:6 of a meaſure; ſo that there was a
generation of one complete meaſure of fixed air,
and
Seet. V.
315
INFLAMMABLE ATR.
1
and this was a clear proof that it could not have
been contained in a combined ſtațe, as I at firſt
imagined, in the inflammable air; ſince then it
muſt have been much heavier than I had ever
found it to be; for, though I found the ſpecific
gravity. of it to be ſomething different at different
țimes (and the preceding experiments were made
with the air of different proceſſes) I had never
found that forty ounce meaſures of this air was
more than two grains heavier than an equal bulk
of common air.
This, indeed, is a remarkable circumſtance with
reſpect to a ſpecies of inflammable air, as it does
not appear by the teſt of lime water to contain
any
fixed air ; but it ought to have weighed more
than one half heavier than common air, to have
actually contained in combination all the fixed air:
that I found after its exploſion with the dephlo-
giſticated air. Indeed, if any quantity of inflam-
mable air, of about the ſame ſpecific gravity with:
common air (which is the caſe with that ſpecies:
of it which I am now conſidering) yieid ſo much
as ſeven tenths of its bulk of fixed air, in confe-
quence of its exploſion with dephlogiſticated air,
it is a proof that at leaſt part of that fixed air was
generated in the proceſs, becauſe ſeven tenths, of
ſuch fixed air would weigh more than the whole.
meaſure of the inflammable air.
Inflam-
i
I
I
4
316
Part III,
OBSERVATIONS ON
Infammable air from ſpirit of wine (made by
franſınitting it in vapour through a red hot earthen
tube) being analized in the manner above-men-
tioned, one meaſure of it, and one of the ſame
dephlogiſticated air that was uſed in the former
experiment, were reduced to one meaſure, and by
waſhing in lime water to 0.6 of a meaſure; fo
that four tenths of its bulk of fixed air had been
generated in the proceſs. The ſtandard of the re-
fiduum was 1.7; ſo that the dephlogiſticated air
had been injured much more than in either of the
former proceſſes, and conſequently it muſt have
contained more phlogiſton.
I found conſiderable variations in the experiments
with this, as well as with ſome other kinds of in-
flammable air. For, in another proceſs, in which
the earthen tube had been filled with bits of cruci-
bles (in order to expoſe more red ſurface to the va-
pour of the ſpirit of wine) the firſt diminution was
to 1.6, the ſecond to 1.4; and the ſtandard of the
reſiduum was 1.84. In another proceſs with this
kind of air, the firſt diminution was to 1.2, and the
fecond to 0.9.
Having procured a quantity of infiammable air,
by tranſmitting ſteam over red hot platina, I ana-
lized it in the ſame manner, and found that the two
meaſúres were reduced by the exploſion to 0.72. It
contained no fixed air, and the reſiduum was of the
ſtandard of 0.9.
Infiam
1
..
SEET. V.
INFLAMMABLE AIR.
317
Inflammable air, procured by making ſteam paſs
over melted brimſtone, being examined in the ſame
manner, the firſt diminution was to o.6, and no fixed
air was found in it. In this reſpect it ſeems to have
been the fame thing with inflammable air from iron,
but the ſtandard of the reſiduum was 0.95; fo that
it ſeems to have contained more phlogiſton. · But as
the quantity of this air was not great, it probably
contained a mixture of other air.
Inflammable air procured in the ſame manner
from melted arſenic, appeared to be very different
from that which was extracted from brimſtone. For
the two meaſures were reduced by the exploſion to
1.15, and by waſhing with lime water, to 0.95; fo
that one fifth of its bulk of fixed air had been gene-
rated. The ſtandard of the reſiduum was o.82.
At the ſame tiine I examined ſome inflammable
air, that had been made by heating bits of crucibles
in alkaline air, and found that the two meaſures were
reduced by the exploſion to 0.96 of a meaſure, that
the reſiduum contained no fixed air, and was of the
ſtandard of o. 8.
The inflammable air that is made froin æther, by
tranſmitting the vapour of it through a red hoc
earthen tube, very much reſembles that which is got
from ſpirit of wine. The two meaſures were reduced
by the exploſion to 1.36, and by waſhing in water to
1.2; ſo that 0.16 of a meaſure of fixed air had been
generated, and the reſiduum was of the ſtandard of 1.9.
Inflam.
T
1
318
OBSERVATIONS ŐN Pärt fit.
Infláinmable air procured by trànſmitting ſteam
over red hot charcoal of metals, in the ſame maħħér
as it is got from other charcoal; produces a conſi-
derable quantity of fixed air. For when the 'expé-
riment was made with this air, the firſt dimunition
was to 1.12, and the ſecond to 0.8; fo that 0.32 of
a meaſure of fixed air was generated, and the
ſtandard of the reſiduum was 1.9. This analyſis
was of the firſt portion that came in the proceſs.
The ſecond was ſomething different. For with
this, the firſt dimunition was to 1.0, and the ſecond
to 0.75, the reſiduum being the ſame as before, viz.
1.9. Thirty ounce meaſures of this air weighed
eight grains leſs than an equal bulk of common air,
Analizing the inflammable air from coak, or the
charcoal of pitcoal produced by ſteam, the firſt
diminution was to 1.15, and the ſecond to 0.95; ſo
that one fifth of its bulk of fixed ait was generated.
The ſtandard of the reſiduum was 1.9. But I muſt
obſerve, that the dephlogiſticated air with which
this experiment was made, was ſo impure as hardly
to deſerve the name. For two meaſures of nitrous
air and one of this, occupied the ſpace of two
meaſures. But this circumſtance may not affect
the quantity of fixed air generated in the proceſs.
Thirty ounce meaſures of this air weighed ten
grains leſs than an equal bulk of common air.
Analizing the inflammable air that was produced
in the fame manner from ſpirit of turpentine, the firſt
diminu-
SEER. V.
319
INFLAMMABLE AIR.
diminution was to 1.7, and the ſecond to 1.6; fo
that only one tenth of fixed air was produced. The
refiduum was of the ſtandard of 1.9. Thirty ounce
meaſures of this air weighed eight grains leſs than an
equal bulk of common air.
When the vapour of ſpirit of wine was made to
pafs over melted metals, inflammable air was 'pro-
duced from it juſt as if no metals had been concerned;
but when I examined the air that was procured in
this manner, it did not appear to be quite the ſame
with that which came from pure ſpirit of wine.
Analyzing the air that was produced in a proceſs
with copper, the firſt diminution was to 1.7, the
fecond to 1.56, and the ſtandard of the reſiduum
was 1.78. Thirty ounce meaſures of this air
weighed feven grains leſs than an equal bulk of
common air.
In another proceſs with infiammable air, pro-
cured in this manner, the firſt diminution was to
1.55, the ſecond to 1.48, and the reſiduum was
of the ſtandard of 1.86. Thirty ounce meaſures
of this air weighed eight grains and a half leſs than
an equal bulk of common air. This air, it is ob-
fervable, produced much leſs fixed air than the
other, and it was alſo ſpecifically lighter than it.
When this proceſs was made with the air pro-
cured by tranſmitting vapour of ſpirit of wine over
melted ſilver, the firſt diminution was to 1.9, the
ſecand
1
320
OBSERVATIONS ON
Part It
1
ſecond to 1.78, and the ſtandard of the reſiduuri
was 1.9: Thirty ounce meaſures of this air weighed
eight grains leſs than an equal bulk of common
air.
In the analyſis of the air procured by this proceſs
from lead, the firſt diminution was to 1.78, the ſe-
cond to 1.6, and the ſtandard of the reſiduum was
'1.78.
I examined, at the ſame time, inflammable air
procured froin bones, and alſo from charcoal, viz.
by tranſmitting ſteam over them when they were
red hot in earthen tubes, after all air had been pre-
viouſly expelled from them by heat. With the
former, the firſt diminution was to 0.67, and the
fecond to 0.58; ſo that the fixed air produced was
extremely inconſiderable, viz. only 0.09 of an
ounce meaſure. The ſtandard of the reſiduum
was 1.47. In the experiment with the air from
charcoal, the firſt diminution was to 1.5, and the
ſecond to 0.74; ſo that the fixed air was 0.76,
and the ſtandard of the reſiduum was 1.7. From
this experiment it may be inferred, as mentioned
before, that inflammable air from bones, is a kind
of medium between that from metals, and that from
charcoal. In another proceſs with air from char-
coal, the firſt diminution was to 0.82, and the
ſecond to 0.63, and the ſtandard of the reſiduum
was 1.37
I made
Seel. V.
321
INFLAMMABLE AIR.
1
I made the following experiment to aſcertain
how much phlogiſton is contained in inflammable
air from charcoal. In five ounce meaſures of this
kind of air, I revived lead from maflicot till it
was reduced to three fourths of an ounce meaſure,
when the lead revived weighed ten grains, and
there remained one ounce meaſure of fixed air.
But the minium itſelf yielded a little fixed air.
It is obſervable, that when wood is heated in
an earthen retort, the firſt air that comes over is
conſiderably different from that which comes in
the middle, or at the end of the proceſs. Indeed
the properties of it are continually changing during
the whole proceſs. The firſt portion burns with
a lambent white fame, like that from burning
wood in an open fire; afterwards the flame is blue,
and towards the end of the proceſs it is conſiderably
exploſive, almoſt like air from jron. Alſo the air
that comes over firſt is very turbid, owing per-
haps, to oily, and other matters, that are rendered
volatile by heat.
Having procured air from diy beech wood, I
examined, in the method deſcribed above, the firſt
portion of it, and alſo one of the middle ones.
The former I found to contain four tenths and a
half of its bulk of uncombined fixed air, the ſecond
portion only two tenths.
only two tenths. Afterwards it is well
Vol. I,
Y
known
322 .'OBSERVATIONS ON: Part III.
1
1
known that air procured in this manner ceaſes to
have any uncombined fixed air in it.
When I examined the firſt portion of air, after
the uncombined fixed air had been ſeparated from
it, the firſt diminution was to 1.36, and the ſecond
to 0.9; ſo that 0.46 of a meaſure of fixed air was
generated, and the ſtandard of the reſiduum was
1.9.
When the ſecond portion was examined,
after the uncombined fixed air was likewiſe ſepa-
rated from it, the firſt diminution was to 1.66,
and the ſecond to 1.46; ſo that the fixed air gene-
rated in the proceſs, was 0.2 of a meaſure, that
is, leſs than in the former experiment, and in nearly
the ſame proportion as the uncombined fixed air
had been. The ſtandard of the refiduum in this
laft caſe was 1.15. At the ſame time, repeating
the experiment with the ſame dephlogiſticated air
and inflammable air from iron, the diminution af
ter the exploſion was to 0.55, and the ſtandard
of the reſiduum was 1.48, which is the uſual reſult
of the decompoſition of inflammable and dephlo-
giſticated air, when both of thein are as pure as
they are generally procured.
There was a great quantity of fixed air produced
by the decompoſition of ſome inflammable air ex-
tracted from fome rich mould in a gun barrel,
which Mr. Young was ſo obliging as to ſend me.
It
4
1
1
+
SPEL. V.
323
INFLAMMABLE AIR.
It burned with a lambent blue flame, and had a
peculiarly offenſive ſinell, the ſame, as he obſerves
to me, that is yielded by air procured from putrid
vegetables. Of this air one twentieth part is un-
combined fixed air. When this was ſeparated
from it, and the remainder decompoſed with de-
phlogiſticated air, the firſt diminution was to 1.4,
and the ſecond to 0.67; ſo that there was a gene-
ration of 0.73 of a meaſure of fixed air, The
reſiduum was of the ſtandard of o.6.
The inflammable air that is procured from caſi
iron has a peculiarly offenſive ſmell. On this ac-
count I had imagined that it might contain more
phlogiſton than common inflammable air, ſo as to
abſorb more dephlogiſticated air than the other.
But this did not appear to be the fact. For when
I mixed one meaſure of each of the kinds of in-
flammable air with four meaſures of common air,
the diminution after the exploſion, was the very
ſame with both, viz. to 1.56.
Though I think it to be unqueſtionable, from
the preceding experiments, that part at leaſt of the
fixed air which is found on the decompoſition of
lambent infammable air is generated in the proceſs;
yet, in another experiment that I måde, it ſhould
ſcem that fixed air, or the elements, as we may
fay, of fixed air, may enter into the compoſition
of
Y 2
A
324
OBSERVATIONS ON Part III.
!
of inflammable air, and actually remain there, with
out being diſcoverable by lime water.
I took a quantity of Naked lime, which had been
long kept cloſe corked in a bottle, and found that
when it was heated in an earthen retort, it gave
air, of which one fifth was for the moft part fixed
air; but in the gun barrel the ſame lime yielded
no fixed air at all, but a great quantity of pure in-
flammable air, of the exploſive kind, like that
which is got from iron alone with water. That
the water in Naked lime will enable the iron of
the gun barrel to yield inflammable air cannot be
queſtioned, but then what became of the fixed
air which the ſame lime would have yielded in an
carthen retort?
This experiment appearing rather extraordinary,
I repeated it with all the attention I could give to
it, and had the following reſult. I heated three
ounces of flacked lime (but which had been ſome
time expoſed to the open air) in an earther tube;
and got from it fourteen ounce meaſures of air,
of which only two meaſures and a half remained
unabſorbed by water, all the reſt being fixed air.
This reſiduum was ſlightly inflammable, but not
perfectly phlogiſticated. For, examining it with
the teſt of nitrous air, the ſtandard of it was 1.6.
1
1
Imine-
+
1
Seet. Vi
325.
INFLAMMABLE AIR:
1
Immediately after this I heated another three
ounces of the fame Naked lime in a gun barrel,
and
got from it about twenty ounce meaſures of
air, of which no part was fixed air, but all inflam-
måble. I expected, howeyer, to have found fixed
air on the decompoſition of this inflammable air
with dephlogiſticated air; but after this proceſs it
appeared to be exactly ſuch inflammable air as is
procured from metals by the mineral acids, or
rather by ſteam. For the diminution of the two
kinds of air was the fame, and though there was
ſome appearance of fixed air in the reſiduum, it
was not ſo much as is found after the decompoſi-
tion of the inflammable air that is procured by
means of ſpirit of ſalt. In this caſe, therefore,
there are no leſs than eleven ounce meaſures and a half
of fixed air abſolutely unaccounted for, unleſs it
be ſuppoſed that it was reſolved into its conſtituent
principles, phlogiſton or dephlogiſticated air, and
that the latter was decompoſed as it was produced.
This, therefore, I think muſt have been the caſe.
Thinking that the two kinds of air might incor-
porate when one of them was generated within the
other, I filled a gun barrel previouſly full of mer-
cury with fixed air, and put the cloſed part of it
into a hot fire. Inflammable air was accordingly
produced, but when the fixed air was ſeparated
from
Y 3
1
326 OBSERVATIONS ON Pari III.
1
from it, it exploded juſt like inflammable air from
iront only.
I made an experiment ſomething ſimilar to this,
by heating iron turnings in five ounce meaſures of
fixed air, when the quantity of it was increaſed
about one ounce meaſure, and there remained one
ounce meaſure and three fourths unabforbed by
water. This was inflammable, and burned with
a lambent blue flame, not like inflammable air
from iron. It ſhould ſeem; therefore, that in this
experiment, three fourths of an ounce meaſure of
infiammable air had been formed by the union of
the fixed air with the phlogiſton from the iron.
This experiment I repeated with the ſame reſult,
and I farther obſerved, that though the inflamma-
ble air procured in this manner did not appear, by
. the teſt of lime water, to contain any fixed air,
yet when it was decompoſed, by being fired toge-
ther with an equal quantity of dephlogiſticated air,
fixed air was found in the refiduum. For the firſt
diminution was to 1.45, and one third of this re-
fiduum was fixed air. From this fact it ſhould
ſeem that, though in ſome caſes, fixed air muſt be
generated by the decompoſition of inflammable and
dephlogiſticated air, yet that inflaminble air, when
chus produced in contact with fixed air, may coma
bine with it, fo as to be properly contained in it,
and
1
1
Seet. A
327
INFLAMMABLE AIR.
1
and in ſuch a manner, as that it cannot be diſcover-
ed by lime water.
I alſo obſerved, after Mr. Metherie, that though
no fixed air be found on the decompoſition of de-
phlogiſticated air with inflammable air procured
by ineans of oil of vitriol; a ſmall quantity, is pro-
duced when the inflammable aír procured by means
of ſpirit of ſalti I did not find, however, more
than a fortieth part of the reſiduum to be fixed
air, when I decompoſed equal quantities of the
two kinds of air:
I 4
BOOK
328
Part T.
OBSERVATIONS ON
1
Β Ο Ο Κ
III.
EXPERIMENTS AND OBSERVATIONS RE.
LATING TO NITROUS AIR.
1
PART
I.
OF THE SOURCE OF NITROUS AIR.
SECTION I.
!
Of nitrous Air from Metals.
VER ſince I firſt read Dr. Hales's moſt excellent
E
Statical Eſays, I was particularly ſtruck with
that experiment of his, of which an account is given,
Vol. I. p. 224, and Vol. II. p. 280, in which
common air, and air generated from the Walton
pyrites, by ſpirit of nitre, made a turbid red mix-
ture, and in which part of the common air was ab-
forbed
i
S2E7, I.
329
NITROUS AIR.
1
ſorbed ; but I. never expected to have the fatisfac-
tion of ſeeing this remarkable appearance, ſuppoſing
it to be peculiar to that particular mineral. Hap-
pening to mention this ſubject to the Hon. Mr. Ca-
vendiſh, when I was in London, in the ſpring of
the year 1772, he ſaid that he did not imagine but
that other kinds of pyrites, or the metals, might
anſwer as well, and that probably the red appear-
ance of the mixture depended upon the ſpirit of
nitre only. This encouraged me to attend to the
ſubject; and having no pyrites, I began with the
ſolution of the different metals in ſpirit of nitre, and
catching the air which was generated in the ſolution,
I preſently found what I wanted, and a good deal
more.
Beginning with the ſolution of braſs, on the 4th
of June 1772, I firſt found this remarkable ſpecies
of air, only one effect of which was caſually obſerved
by Dr. Hales ; and he gave ſo little attention to it,
and it has been ſo much unnoticed ſince his time,
that, as far as I know, no name has been given to
it. I therefore found myſelf, contrary to my
firſt
reſolution, under an abſolute neceſſity of giving a
name to this kind of air myſelf. When I firſt be-
gan to ſpeak and write of it to my friends, I hap-
pened to diſtinguiſh it by the name of nitrous air,
becauſe I had procured it by means of ſpirit of nitre
pnly.
+
1
I have
1
330
OBSERVATIONS ON
Part 1
I have found that this kind of air is readily pro-
cured from iron, copper, braſs, tin, ſilver, quick-
ſilver, biſmuth, and nickel, by the nitrous acid only,
and from gold and the regulus of antimony by
aqua regia. The circumſtances attending the folu-
tion of each of theſe metals are various, but hardly
worth mentioning, in treating of the properties of
the air which they yield; which, from what metal
foever it is extracted, has, as far as I have been able
to obſerve, the very ſame properties.
Nitrous air is procured from all the proper mie-
tals by ſpirit of nitre, except lead, and from all the
ſemi-metals that I have tried, except zinc. For
this purpoſe I have uſed biſmuth and nickel, with
ſpirit of nitre only, and regulus of antimony and
platina, with aqua regia.
I did not endeavour to aſcertain the exact quan-
tity of nitrous air produced from given quantities of
all the metals which yield it ; but the few obſerva-
tions which I firſt made for this purpofe I ſhalt recite
in this place :
dwt. gr.
I
I
141
21
,6 o of ſilver yielded 174 ounce meaſures.
5 19 of quickſilver 42
2} of copper
O of braſs
© 20
20 of iron
16
5 of biſmuth 6
O 12
12 of nickel
4
Having,
I
1
Sect. I.
NITROUS AIR.
33.1
1
Having, at another time, diffolved ſilver, copper,
and iron, in equal quantities of ſpirit of nitre diluted
with water, the quantities of nitrous air produced
from them were in the following proportion ; from
iron 8, from copper 61, from filver 6. In about
the ſame proportion alſo it was neceſſary to mix wa-
ter with the ſpirit of nitre in each caſe, in order to
make it diffolve theſe metals with equal rapidity,
ſilver requiring the leaſt water, and iron the moſt.
That iron contains more phlogiſton than copper,
is probable from the much greater quantity of nitrous
air that it yields. At one time I found that two
penny-weights of iron diſſolved in ſpirit of nitre,
diluted with rain-water, yielded forty five, ounce
meaſures of nitrous air, when the ſame quantity of
pure copper, treated in the ſame manner, yielded
only ſixteen ounce meaſures.
I have obſerved that I got little or no air by dif-
folving lead in ſpirit of nitre. I afterwards, how-
ever, made another attempt of this kind, and with
a little better ſucceſs. I poured ſmoking ſpirit of
nitre into a phial with a ground-ſtopper and tube,
containing one ounce meaſure and a half, filled with
ſmall leaden ſhot, ſo as to leave no common air ac
all, either in the phial or in the tube ; and I placed it ſo
as to receive the air that might come from it in water:
After waiting an hour, in which little or no air
was produced, I applied the flame of a candle,
though
1
1
I
332
OBSERVATIONS
Part to
ON
though not very near to it, and in theſe circum-
ſtances I got about an ounce meaſure of air ; but
upon ſome water ruſhing into the phial, while the
candle was withdrawn, air was produced very plena
tifully. I collected, in all, about a quarter of a
pint, and might probably have got much more ;
but that the ſalt formed by the ſolution of the lead
had ſo nearly cloſed up the tube, that I thought pro-
per to diſcontinue the proceſs. The air, both of
the firſt and of the laſt produce, was of the fame
quality, and ſo far nitrous, that two meaſures of
common air, and one of this, occupied the ſpace of
two meaſures only; excepting that the very firſt and
very laſt produce, mixed with common air, took up
a little more room than that which I got in the mid-
dle of the proceſs. When the air was produced
very faſt, it was exceedingly turbid, as if it had been
filled with a white powder.
I have generally found it moſt convenient to get
nitrous air from copper, on account of the pretty
equable ſolution of that metal in the nitrous acid.
If iron be made uſe of, the proceſs is much more
difficult, the increaſe of heat, and other circum-
ſtances, making a very great difference in the ra-
pidity of the ſolution; ſo that very often, when the
efferveſcence is very moderate at the beginning, it
will be ſo violent after a ſhort time, that the greateſt
part
of the acid will be thrown out of the phial,
and
Sect. I.
NITROUS
AIR.
333
and conſequently the effect of it will be loſt. This
difficulty, however, only attends the pouring of a
diluted fpirit of nitre upon a quantity of nails, or
other ſmall pieces of iron, in order to effect a com-
plete faturation of the acid that is made uſe of at one
time, which I have found to be the moſt convenient
upon the whole. If thicker pieces of iron be put
to the acid, by which means the quantity of ſur-
face expoſed to its action is not conſiderable, the
produce of air may be made pretty regular ; but
I have not, upon the whole, found this method fo
convenient as the other.
Having ſometimes, however, procured nitrous
air from iron by this proceſs, I have noted ſome cir-
cumſtances attending this ſolution, which, becauſe
they are a little remarkable, I ſhall here recite.
When I put a thick piece of iron into a quantity of
very ſtrong ſpirit of nitré, it was not at all affected
by it : but by the application of a boiling heat it
yielded nitrous air, about ten times the bulk of the
acid. When a quantity of water was-poured upon
the ſpirit of nitre and iron, it became of a beautiful
green or blue colour, and no motion was perceived
in it for about a minute, when it burſt out all at once
into the moſt violent efferveſcence imaginable, and
a prodigious quantity of nitrous air was inſtantly
produced. It will be evident from ſubſequent ex-
periments, that a certain proportion of water is ne-
4
ceffary
1
334
OBSERVATIONS ON
Part I.
{
ceſſary to the conſtitution of nitrous air, and there-
fore the diluted acid is more proper for this purpoſe.
Mr. Delaval was ſo obliging as to inform me that
all aftringent vegetables, as galls, the peruvian bark,
and greez tea, diſſolve with peculiar rapidity in the
nitrous acid, in a manner not unlike the folution of
ſeveral of the metals in the ſame acid; and that a
great quantity of air is generated in the proceſs. I
immediately made the experiment with galls, and
was really ſurprized at the effect. The ſolution
was, indeed, aſtoniſhingly rapid; but the quantity
of air produced by it was not, ſeemingly, greater
than would have been yielded by the ſame bulk of
any other vegetable ſubſtance, diſſolved in the ſame
acid, with more heat. The air was alſo of the ſame
quality with that which is yielded by moſt vegetable
fubftances. In this caſe, more than half of it
was fixed air, making lime water turbid, and
the reſidyum was ſo far nitrous, that two mea-
fures of common air and one of this, occupied the
ſpace of two meaſures and a half,
+
1
1
SEC.
1
Sect. II.
335
NITROUS AIR.
1
SECTION
II.
Of nitrous Air from Vapour of Spirit of Nitre and
Water.
I
WAS no ſooner in poſſeſſion of nitrous vapour,
than I ſaw opened to me an entire new field
for experiments, by means of a rapid ſolution of
biſinuth in ſpirit of nitre, of which a fuller account
will be given under the article of nitrous acid.
Three methods preſently occurred to me of
ap-
plying this nitrous vapour, in order to form com-
binations with other ſubſtances, by which means
only its proper nature, and peculiar powers, could
be diſcovered. One was, to put the ſubſtance into
a clean phial, and then to throw a ſtreain of the va-
pour upon it. Another was, firſt to fill the phial
with the vapour, by which method the quantity of it
might be, in ſome meaſure, aſcertained, and then
to introduce the ſubſtance to it at the mouth of the
phial. Laſtly, if the ſubſtance was fluid, I could
plunge the tube, through which the vapour was
tranſmitted, as deep as I pleaſed into it, and there
by diffuſe the yapour through the whole body of it.
The ſecond of theſe methods was the firſt I had
recourſe
336
Part 1
OBSERVATIONS
ON
recourſe to, though foon afterwards I applied the
firſt, and not long after that the third. And as I
could not well produce this acid vapour at all with-
out generating enough to fill a great number of
phials, I generally placed fix, eight, or ten of them
in a row, filling them with the vapour one after
another, and ſometimes ſupplying them all ſeveral
times in the courſe of one proceſs.
The firſt experiment that I made with water,
was to pour a ſmall quantity of it into a phial filled
with this vapour; when, ſhaking it about, it be-
came, as would eaſily be ſuppoſed, genuine fpirit
of nitre ; but it was weak and colourleſs.
After this, I threw a ſtream of the vapour upon
a ſmall quantity of diſtilled water, in a large phial;
ſhaking it'now and then, to promote the abſorption
of the vapour ; when I obſerved that the water
preſently became warm, then began to ſparkle
very much, air iſſuing from all parts of it verò
copiouſly; and after this it aſſumed a light blue
colour; in' which ſtage of the proceſs, it was, I
'doubt not, the very ſame thing that Mr. Woulfe
had found by impregnating water with the ſuper-
abundant nitrous vapour, in his method of diſtil-
ling ſpirit of nitre. But, whereas he ſays his blue
liquor continued blue, I found that mine preſently
loſt its colour on being expoſed to the open air,
cmitting a copious red fume:
Finding
Scar. Ir.
337
NITROUS AIR
1
I got a
Finding that, in this manner of impregnating
water, I foon gained the point of ſaturation, by as
much of the vapour eſcaping as I could readily
throw into it, I contrived to impregnate the water
more effectually, in the following manner.
veſſel, b, fig. 2, Pl. V. in the form of a phial with
a ground ſtopper, and two holes in the bottom;
which, however, was to be placed uppermoſt when
it was uſed. To one of theſe holes was fitted, by
grinding, a glaſs fyphon, one end of which was fitted
in the ſame manner to the long phial in which the
folution of the metal for the production of the va-
pour was made, while the other end of it went to
the bottom of the veffel above mentioned, and
which contained the water; ſo that whatever ya-
pour was brought into the veſſel by it, muft necef-
farily paſs through the whole body of the water ;
and to the other hole in this veſſel there was fitted,
by grinding alſo, the end of a bent tube, which con-
veyed the ſuperfluous air, or vapour, into a com-
mon recipient. But ſometimes I had ſeveral of
theſe veſſels 'connected together, as repreſented,
fig. 3, ſo that the air and vapour diſcharged
from the firſt of them muſt neceſſarily paſs
through the water in the next, and that which was
diſcharged in this mụſt paſs through the water in
the following, &c.
Vol. I.
Z
Making
338
Part I.
OBSERVATIONS ON
1
Making the experiment in this more accurate
manner, ſo that the water had an opportunity of
becoming thoroughly impregnated, I made the fol-
lowing obſervations. The water, after becoming
warm, began, as before, to ſparkle, and emit air ;
after which it became blue, ſtill continuing to give
air in much greater plenty than before. After this
the water became green, about which time the emis-
ſion of air ceaſed; and laſtly, after the green colour
had deepened very much, ſo as to appear almoſt
black, when viewed in the ſame direction with the
light that fell upon it, a yellowiſh tinge was perceived
to be diffuſed through the green colour ; and this
was the laſt ſtate to which I could bring the water
by this impregnation.
I alſo obſerved that, about the time that the wa-
ter in the firſt of theſe veſſels became blue, that in
the next began to ſparkle ; and when the water in
the firſt turned green, which was probably effected
in no other way than by the mixture of the yellow
(which diſtinctly appeared afterwards) with the
preceding blue, the water in the next veffel be:
came blue, and that in the following to ſparkle,
&c.
One of the moſt extraordinary circumſtances in
this whole proceſs, is the production of air from
the water in the two firſt ſtages of it, viz. while it
is tranſparent, and while it is blue, before it be-
1
comes
1
Se&. II.
339
NITROUS AIR.
comes green. At firſt I concluded that this was
phlogiſticated air ; this kind of air having been the
produce of a ſimilar proceſs for the impregnation of
oil with the nitrous vapour. But having filled a
phial with this water, at the time that it was dif-
charging air moſt copiouſly, and having placed it
inverted in a baſon of the ſame, I preſently got a
conſiderable quantity of it, and found it to be all
pure nitrous air, poffeffed of the peculiar proper-
ties of that kind of air in as great a degree as any
whatever, and that it contained no portion of fixed
air.
The quantity of nitrous air produced in this man-
ner is very extraordinary. When I filled a phial
with the water in the ſtate of emitting air, and in-
verted it in a baſon of water, it preſently almoſt filled
it, expelling the water. But when I filled a phial
with a ground ſtopper and tube with the water, and
caught all the air that came from it, with and with-
out heat, I got at one time more than ten times the
bulk of the water, all pure nitrous air.
This will appear the more extraordinary, if it be
conſidered, that water cannot be made to imbibe
more than about one tenth of its bulk of nitrous air.
The production of it in this caſe, therefore, is quite
another thing, and muſt have a different cauſe ;
though, had the quantity of it been ſmall, it might
have
Z 2
t
340
Part I.
OB'S ERVATIONS ON
1
have been imagined, that the nitrous air from the
biſmuth having impregnated the water, as, in ſome
degree, it neceſſarily muſt, this nitrous air might
have come from that ſolution.
So great is this diſcharge of nitrous air, that if
the impregnated water be left to itſelf, it will con-
tinue to emit air for a day or two; ſo that it is not
improbable, but that it may, from firſt to laſt, yield
fifteen or twenty times, its bulk. On this account,
if this water be confined in thin phials, it will endan-
ger the breaking of them ; and the ground ſtoppers
of ſtrong phials have often been thrown out by it
with great violence.
SEC.
Sea, 111.
341
NITROUS AST R.
SECTION
III.
Of the increaſed Produce of nitrous Air by previouſly
converting the Acid into Vapour.
AVING obſerved the remarkable production
of nitrous air from water impregnated with
nitrous vapour, in the following experiment I more
accurately compared the quantity of nitrous air
pro-
duced by pouring the impregnated water upon cop-
per, with the quantity produced by an equal quantity
of ſpirit of nitre and copper, without impregnating
water with the vapour that the acid would have
yielded.
Having diſſolved a quantity of biſinuth in a given
quantity of ſpirit of nitre, and having made the
vapour which was raiſed by the ſolution paſs through
a quantity of water, I poured this water on ſome
clippings of copper, in a phial with a ground ſtop-
per and tube, and found that it yielded one ſixteenth
more nitrous air than the ſame quantity of nitrous
acid diluted with water, and applied to the copper
in the ſame manner, would yield ; the heat of a
candle being applied in both theſe caſes till no more
air could be procured. No allowance alſo was
made
23
1
:
1
342
Part 1.
OBSERVATIONS ON
made for a conſiderable quantity of red vapour which
was loſt in decanting the water, or for that which
remained in the large phial in which the ſolution
was inade, or for the acid that was united with the
biſmuth in the ſolution. The air yielded by the
impregnated water and copper was thirteen ounce
meaſures, and the ſolution of the biſinuth uſed in
this experiment being diluted with water, and then
poured upon the copper, yielded fix ounce meaſures
and a half, which alone is more than half as much
as the original quantity of the acid yielded. Upon
the whole, therefore, ſpirit of nitre, uſed in this
manner, may be made to yield, by means of
copper,
one half more nitrous air than can be procured by it
when applied in the uſual way.
For my greater ſatisfaction, I alſo repeated an
experiment ſimilar to the former, with water im-
pregnated with nitrous vapour, in the proceſs for
making dephlogiſticated air from fpirit of nitre and
red lead, and the reſult was as follows. Having
put ſix penny weights of ſtrong ſpirit of nitre upon
a quantity of red lead, and heating the mixture in
a gun barrel, I made all the air, together with the
redundant acid, paſs through a quantity of water ;
and found that the water, poured upon copper, would
have yielded fourteen ounce meaſures of nitrous air,
(a part of the water having produced nitrous air in
that proportion to the whole) but the fame quantity
of
SeEt. III.
343
NITROUS AIR.
1
of the acid, even with the aſſiſtance of heat, yielded
only about eleven ounce meaſures and a half.
I alſo mixed with three ounces of red lead as much
ſpirit of nitre as occupied the ſpace of eight penny-
weights of water, when the produce was forty
ounce meaſures of air, of which about five ounce
meaſures was fixed air. The water through which
it had paſſed in the veſſel No. 2, Pl. V. after
making all proper allowances, and uſing a variety
of precautions in applying it to the copper, too
minute to be mentioned here, I judged to produce
in all twenty four ounce meaſures of nitrous air,
which I found to be clearly more than the original
quantity of this acid would have yielded.
The above-mentioned experiments were made
before I had much ſuſpicion of the great difference
in the produce of nitrous air occaſioned by the ap-
plication of heat, which is ſometimes very con-.
ſiderable, and by no means in the fame proportion
in all caſes; ſome kinds of the acid yielding al-
moſt the whole produce without external heat,
and other kinds hardly more than one half. I
therefore thought it neceffary to go over this pro-
ceſs once more with a view to this circumſtance,
and the reſult was ſtill the ſame as before, the
water through which the generated air had paſſed
producing more nitrous air than the whole quan-
tity
1
Z 4
344
Part 1.
OBSERVATIONS ON
1
tity of the acid employed in the experiment would
have done.
The quantity of acid which I uſed at this time
occupied the ſpace of four pennyweights of water,
and when applied to copper I could not, with any
application of heat, make it yield more than twelve
ounce meaſures and a half. But when the ſame
quantity of this acid had been mixed with red lead,
which was afterwards put into a gun barrel, and had
been made to yield all the air that could be extract-
ed from it, one ſeventh part of the water through
which the air had paſſed produced two ounce mea-
ſures of nitrous air; ſo that the whole quantity
would have been fourteen ounce meaſures; and
this was after the water had been decanted firſt
from the veſſel repreſented fig. 2, into another
phial, and ſome time afterwards, from that into the
ſmall phial containing the copper. And it ſhould
be conſidered, that after this proceſs (if it be con-
tinued till the water begin to emit air, a circum-
ſtance of which an account will be given hereafter)
it is ſo exceedingly volatile, that it is not poſſible
pour
the water from one veffel to another with
out the diſcharge of very copious red fumes, in
which a good deal of the acid muſt be loft. There
muſt alſo be fome loſs of that nitrous air which is
emitted by the water itſelf; and I doubt not that
the
to
1
Seet. Ill.
345
NITROUS AIR.
the increaſe in the produce of nitrous air in theſe
experiments is from this ſource, viz. that which
is ſupplied from the water, in conſequence of the
impregnation with nitrous vapour. Whereas when
the acid is much dephlogiſticated, a great part
of
it becomes combined with the menftruum, and
therefore has no effect in producing nitrous air.
I hardly remember any thing, in the whole
courſe of my experimenting, that appeared more
extraordinary than this. It ſeemed as if there
was an increaſe, inſtead of any loſs of acid, after
part of it muſt have been employed in forming
the air, and part alſo had been neceſſarily loſt in
the courſe of the experiment.
I conſulted ſeveral of my chemical friends upon
this ſubject; but they were all of them as much
at a loſs to account for the fact as myſelf.
That the giving of nitrous air depends upon
phlogiſton, is evident from the phenomena which
attend the ſolution of iron in phlogiſticated and
dephlogiſticated acids. Pouring a ſmall quantity
of phlogiſticated nitrous acid into a large quantity
of water, which had iron wire in it, it preſently be-
came of a dark colour ; but this was ſoon preci-
pitated, and the folution aſſumed a lighter colour.
I then poured off the ſolution, which was of a ſlight
brown colour, and pouring into it more phlogiſti-
cated
1
7
1
346
Part I.
OBSERVATIONS
ON
cared nitrous acid, it iminediately became of a very
dark colour, and emitted air copiouſy.
On examination it appeared to be ſtrong nitrous
air. After the emiſſion of this air, the dark colour
diſappeared. Theſe phenomena, therefore, exactly
reſembled thoſe of a ſolution of green vitriol, which
affumes a dark colour by imbibing nitrous air,
and becomes clear again by the expulſion of it.
The dark green ſpirit of nitre had the ſame effect
as the brown phlogiſticated acid, but the dephlo-
giſticated nitrous acid had no ſuch effect.
It is eaſy to make a pretty ſtrong ſolution of
iron in dephlogiſticated nitrous acid that ſhall be
green and give no air, if it be kept very cold
during the proceſs. But if phlogiſticated nitrous
· acid be poured into the folution, it preſently be-
comes very black, and emits air. This blackneſs
will ſometimes, if the nitrous acid be very volatile,
go off almoſt immediately; but in all caſes it will
do ſo in time, and leave the liquor like water, or
with a ſlight tinge of yellow; owing probably to
part of the ochre having imbibed pure air, and
thereby tending to become red.
Nitrous air alſo admitted to a green folution of
iron in nitrous acid immediately turns it black,
juſt as it does a folution of green vitriol.
+
Phlo-
Sect. IV.
347
NITROUS AIR.
Phlogiſticated nitrous acid dropped into a folu-
tion of green vitriol alſo makes it black. The
green
folution of iron in ſpirit of nitre, yields very
little air by heat, and this is not nitrous air. When
charcoal was put into it, and heated, it alſo gave
little or no air,
SECTION
IV.
of the Produétion of nitrous Air by Means of phlo-
giſticated nitrous Acid.
THE
1
HE only method that I have uſed to meaſure
the ſtrength of different kinds of nitrous acid,
has been to find the quantity of nitrous air that
a given quantity of the acid would yield, when
diluted with equal quantities of water, from the
ſame quantity of copper. It is neceſſary that theſe
circumſtances be pretty rigorouſly attended to; for
otherwiſe conſiderable miſtakes will be made. For
in different circumſtances the produce of air from
equal quantities of the fame acid will be conſider-
ably different. I ſhall here ſubjoin a few of my
obſervations of this kind, that the reader may be
apprized of them, and alſo of the importance of
attending to other differences of a ſimilar nature.
.
In
+
348
Part I.
OBSERVATIONS ON
one.
In a ſmall phial, and with a briſk efferveſcence,
the quantity of four penny-weights of water of a
ſtrong ſpirit of nitre produced fixteen ounce mea-
ſures of nitrous air; whereas, in a large phial,
diluted with more water, and conſequently with a
leſs efferveſcence, the ſame quantity of the ſame
acid yielded only fourteen ounce meaſures of air.
Alſo the quantity of copper (which was ſuch cut-
tings as the braziers commonly make) in the finall
phial was about half as much as that in the large
With the ſame quantity of ſpirit of nitre in
the large phial, and with the application of the
heat of a candle, I got fifteen ounce meaſures of
air. At another time the ſame quantity of the
acid without heat has not yielded much more than
twelve ounce meaſures.
I have frequently obſerved that, unleſs the quan-
tity of acid was ſufficient to produce a briſk effer-
veſcence, the produce of air has been greatly de-
ficient, the briſkneſs of the efferveſcence occaſioning
a conſiderable heat, which is always favourable to
the ſolution of metals. But the application of equal
degrees of heat will not make the produce of air
equal, unleſs other circumſtances be attended to.
Whenever I have compared the ſtrength of acids
in this manner I have ſcrupulouſly attended, as far
as I could, to all theſe circumſtances.
Having
Sect. IV.
349
NITROUS AIR.
1
Having procured nitrous acid in the ſeveral
ſtates above-mentioned, viz. the original pale co-
loured acid, that out of which the colour had been
expelled by heat, that which had been diſtilled
again from freſh nitre, and that which had been
phlogiſticated by heat in cloſe veſſels, I tried the
ſtrength of them all by the folution of copper,
meaſuring the quantity of nitrous air that equal
· bulks of them all other circumſtances being the
fame) produced, and obſerved that a quantity of
each occupying the ſpace of two pennyweights
cighteen grains of water yielded as follows, viz.
Ounce Meaſures.
14
II
1
II
II
The original pale coloured acid,
The colourleſs,
That rediſtilled from nitre,
That coloured by heat,
This highly phlogiſticated acid hiſſed very much
when mixed with water. The produce of air was
more or leſs accelerated during the courſe of the
folution in all of them, but moſt of all when I
uſed the pale coloured acid. I muſt obſerve that,
in making this colourleſs acid, I uſed more heat
than was neceſſary, and therefore weakened it too
much, though it is certainly impoſſible to expel
the colouring phlogiſton without expelling, at the
ſame time, the acid to which it is attached. It is
ſomething remarkable, that the phlogiſton, in this
par-
+
350
OBSERVATIONS ON
Part I.
particular ſtate, ſhould attach itſelf wholly to one
part of the acid only, though mixed with the reſt
of the acid, coinbined alſo with phlogiſton, but in
a different ſtate. Theſe experiments, however,
ſufficiently demonſtrate this to be the caſe.
It is ſomething remarkable, that though a great
quantity of nitrous air is produced by the folution
of copper in a diluted nitrous acid, no air at all is
procured by a ſolution of the fame metal in the
ſtrong acid.
There is not even any appearance
of air being formed, and afterwards abforbed by
the acid, as in the ſimilar ſolution of mercury.
Having faturated a quantity of ſtrong ſpirit of
nitre with copper, of which it diffolves but a ſmall
quantity, I diſtilled it in a green glaſs retort. The
firſt part of the acid that came over was orange
coloured, from being of a deep green; but the
last was quite tranſparent and weak. No air, that
I could perceive, was produced, but a tubulared
receiver being made uſe of, a ſinall quantity could
not be diſcovered. There was not water enough
to form nitrous air.
1
SEC
SEET. V.
351
NITROUS AIR.
1
SECTION V.
Of Air from Gunpowder.
EING deſirous of knowing what kind of air
was produced by the exploſion of gunpowder,
I, for that purpoſe, mixed equal quantities of ſul-
phur and falt-petre, both finely pounded, and put
them into a tall glaſs veſel. The production of air
was very rapid and copious, and ſo highly nitrous,
that two meaſures of common air, and one of this,
occupied the ſpace of two meaſures and a quarter.
Since the produce of air from ſpirit of nitre and char-
coal is the very fame with this, viz. nitrous air, it
cannot be doubted but that nitrous air is alſo pro-
cuced in the explofion of gunpowder, which is
compoſed of thoſe ingredients; the ſpirit of nitre
not being deſtroyed, or ſo far decompoſed as that
its acid nature is loft, but only entering into the com-
poſition of this ſpecies of air.
Having got nitrous air from a mixture of ſalt-
petre and ſulphur, and alſo from ſpirit of nitre
and charcoal, I concluded that nitrous air muſt be
produced in the firing of gunpowder; and it fa-
vours this ſuppoſition, that when I fired gunpowder
$
in
1
352
Part I.
OBSERVATIONS ON
1
in common air, the air was in part phlogiſticated by
it. It is poſſible, however, that when the heat is
applied very ſuddenly, the proper earth of the char-
coal, and alſo that of the nitre itſelf may, in parts
unite with the nitrous acid, and thereby compoſe a
better kind of air than was produced in thoſe expe-
riments, in which the proceſs was flow, ſo that the
ſpirit of nitre had an opportunity of faturating itſelf
with the phlogiſton of the ſubſtances mixed with it,
without touching the pure earth, and therefore the
produce was nitrous air only.
I have been led to entertain this ſuſpicion in con-
ſequence of being invited by Mr. Woulfe to examine
the air that is produced in making clydus of nitre,
both with ſulphur and with charcoal; when, in
both the cafes, I own, the air that was produced ap-
peared to be conſiderably better than, from the ma-
terials, and the manner of making the experiments,
I ſhould have imagined it could have been. There
was, indeed, a conſiderable quantity of common air
in every thing belonging to the apparatus, which
was not conſtructed with any view to the produce
of air; but the proceſs was continued ſo long, and
the quantity of air produced was ſo great, that I
do not, in my own mind, make much allowance
for that circuinſtance.
It appeared that the air produced from the clyſſus
made with ſulphur, contained one twelfth of fixed
air,
.
Sct. V.
353
NITROUS AIR.
air, making lime water turbid, and the remainder
was phlogiſticated air, neither affecting common
air, nor being affected by nitrous air, and extin-
guiſhing a candle. And the air that was produced
in the proceſs with charcoal, contained no more than
one cwentieth of fixed air, and the remainder, though
it extinguiſhed a candle, was ſo little phlogiſticated,
that two meaſures of it and one of nitrous air occu-
pied the ſpace of two meaſures and a quarter.
VOL. I.
PART
354
Part II.
OBSERVATIONS ON
P ART
II.
OF THE PROPERTIES OF NITROUS AIR.
SECTION I.
Of nitrous Air as the Teſt of the Prurity of reſpir.com
ble Air.
NE of the moſt conſpicuous properties of
this kind of air is the great diminution of
any quantity of common air with which it is mix-
ed, attended with a turbid red, or deep orange
colour, and a conſiderable heat. The ſmell of it,
alſo, is very ſtrong, and remarkable, but very much
reſembling that of ſmoking ſpirit of nitre.
The diminution of a mixture of this and common
air is not an equal diminution of both the kinds, which
is all that Dr. Hales ſuppoſed he had obſerved, but of
about one fourth of the common air, and as much
of
1.
5
1
NITROUS AIR:
1
Sect. I.
355
of the nitrous air as is neceſſary to produce that
effect; which, as I have found by many trials, is
about one third as much as the original quantity
of common air. For if one meaſure of nitrous
air be put to two meaſures of common air, in a
few minutes (by which time the efferveſcence will
be over, and the mixture will have recovered its
tranſparency) there will want about one ninth of
the original two meaſures; and if both the kinds
of air be very pure, the diminution will ſtill.
go
on fowly; till in a day or two, there will remain
only one fifth of the original quantity of common
air. This farther diminution, by long ſtanding,
I had not obſerved at the time of my firſt publica-
tion on this ſubject.
I hardly know any experiment that is more
adapted to amaze and ſurprize than this is, which
exhibits a quantity of air, which, as it were, devours
a quantity of another kind of air half as large as
itſelf, and yet is ſo far from gaining any addition
to its bulk, that it is conſiderably diminiſhed by
it. If, after this full ſaturation of common air with
nitrous air, more nitrous air be put to it, it makes
an addition equal to its own bulk, without
pro-
ducing the leaſt redneſs, or any other viſible ef-
fect.
In order to judge whether the water contributed
to the diminution of this mixture of nitrous and
Аа 2
coin-
356
OBSERVAT LO.NIS ON
Part I.
1
cominon air, I made the whole proceſs ſeveral times
in quickſilver, uſing one third of nitrous, and two.
thirds of common air, as before. In this caſe the
redneſs continued: a very long time, and the dimic
nution was not ſo great as when the mixture had
been made in water, there remaining one ſeventh
more than the originali quantity of common air.
This mixture ftood: all night upon the quick-
ſilver; and the next morning. I obſerved that it
was no farther diminiſhed upon the admiſſion op.
water to it, nor by pòuring it ſeveral times through
the water, and letting it ſtand in water two days,
Another mixture, which hadi ſtood about fix
hours on the quickſilver, was diminiſhiedi a little.
more upon the admiſſion of water, but was nexers
leſs than the original quantity of common air. In
another caſe, however, in which the mixture. had;
ſtood but a very ſhort time. in quickſilver, the fare
ther diminution, which took place upon the ad-
miffion of water, was, much more conſiderable; fo
that the diminution, upon the whole, was very.
nearly as great as if the proceſs, had: been intirely.
in water.
It is evident from theſe experiments, that the
diminution is in part owing to the abſorptian by
the water; but that when the mixture is keptai
long time, in a ſituation in which there is, na
water to abſorb any part of it, it acquires a.con-
ſtitution,
1
Sech 1.
NITROUS
AIR:
357
s
ftitution by which it is afterwards incapable of
being abſoibed by water, or rather, there is an
addition to the quantity of air by nitrous air pro-
duced by the ſolutioh of the quickſilver.
It is exceedingly remarkable thất this efferver-
cence and diminution, occaſioned by the mixture
of nitrous air, is peculiar to common air; or air fit
for reſpiration; and, as far as I can judge from á
great number of obſervations, is at leaſt very near-
ly, if not exactly, in proportion to its fitneſs for
this purpoſe ; ſo that by this means the goodneſs
of air may be diſtinguiſhed much more accurately
than it can be done by putting mite, or any other
aniinals; to breathe ih it.
This was a moſt agreeable diſcovery tó me, as
I hope it may be an uſeful one to the public;
eſpecially as, from this time, I had no occaſion for
fo large a ſtock of mice as I had been uſed to
keep for the purpoſe of theſe experiments, uſing
them only in thofe which required to be very de-
ciſive; and in theſe caſes I have ſeldom failed to
know beforehand in what manner they would be
affeefed.
It is alſo remarkable that, on whatever account
air is unfit for reſpiration, this fame teſt is equally
applicable. Thus there is not the leaſt effervef-
cence between nitrous and fixed air, or inflamma-
ble air, or any ſpecies of diminiſhed air. Alſo the
degree
A a 3
2
358
Part II:
OBSERVATIONS ON
th
degree of diminution being from nothing at all
to more than one fourth of the whole of any quan-
tity of air, we are, by this means, in poffeffion of a
prodigiouſly large ſcale, by which we may diſtin,
guiſh very ſmall degrees of difference in the good,
neſs of air.
I have not attended much to this circumſtance,
having uſed this teſt chiefly for greater differences;
but, if I did not deceive myſelf, I have perceived
a real difference in the air of my ſtudy, after a few
perſons have been with me in it, and the air on
the out ſide of the houſe.
By means of this teft I was able to determine
what I was before in doubt about, viz. the kind as
well as the degree of injury done to air by candles
burning in it. I could not tell with certainty, by
means of mice, whether it was at all injured with
reſpect to reſpiration; and yet if nitrous air may
be depended upon for furniſhing an accurate teſt,
it muſt be rather more than one third worſe than
common air, and have been diminiſhed by the
fame general cauſe of the other diminutions of air.
For when, after, many trials, I put one meaſure of
thoroughly putrid and highly noxious air, into
the ſame veſſel with two meaſures of good whole-
ſome air, and into another veſſel an equal quantity,
viz. three meaſures of air in which a candle had
burned out; and then put equal quantities of ni-
trous
1
:
+
Set. I.
NITROUS
AIR.
359
1
1
trous air to each of them, the latter was diminiſh-
ed rather more than the former.
It agrees with this obſervation, that air in which
a candle has burned is farther diminiſhed both by
putrefaction, and a mixture of iron filings and ſul-
phur; and, I therefore take it for granted, by every
other cauſe of the diminution of air. It is pro-
bable, therefore, that this air is air ſo far loaded
with phlogiſton, as to be able to extinguiſh a
candle, which it may do long before it is · fully
faturated.
I would obferve, that it is not peculiar to nitrous
air to be a teſt of the fitneſs of air for reſpiration.
Any other proceſs by which air is diminiſhed, and
made noxious, anſwers the fame purpoſe. Liver
of ſulphur for inſtance, the calcination of metals,
or a mixture of iron filings and brimſtone will do
juſt the ſame thing; but the application of them
is not ſo eaſy, or elegant, and the effect is not ſo
ſoon perceived. In fact, it is phlogiſton that is the
teſt. If the air be ſo loaded with this principle
that it can take no more, which is ſeen by its not
being diminiſhed in any of the proceſſes above-
mentioned, it is noxious; and it is wholeſome in
proportion to the quantity of phlogiſton that it is
able to take.
This, I have no doubt, is the true theory of the
diminution of common air by nitrous air, the rede
neſs
F
Aa 4
360
OBSERVATIONS ON Part II.
neſs of the appearance being nothing more than
the uſual colour of the fumes of ſpirit of nitre,
which is now diſengaged from the ſuperabundant
phlogiſton with which it was combined in the nitrous
air, and ready to form another union with any
thing that is at hand, and capable of it.
I found, very unexpectedly, that a conſiderable
difference would be made in the dimenſions of the
mixture of air by a circumſtance in the manner of
mixing them that one would not readily ſuſpect,
and I was not at firſt able to account for it. My
uſual method, as I have obſerved in the Introduce
tion, has been to mix equal meaſures of nitrous
and common air in a low jar, and then to transfer
the air into a graduated tube, three or four feet
long. What I obſerved is, that I could make a
difference of five hundred parts of a meaſure by
making the air run up the long tube quickly or
Nowly. The more ſlowly it aſcended, the leſs
ſpace it occupied. To aſcertain whether it depend :
ed merely upon the two kinds of air being ſo
much longer together in the wider veſſel, or in
the funnel through which it was poured into the
tube, I made the mixtures over night, and tranf,
ferred them into the graduated tube the next
morning; but I ſtill found the ſame difference,
depending upon the circumſtance above-mentioned.
It has been obſerved by Mr. Cavendiſh, that agis
tation
-D
1
:
DET. I. NITROUS AIR.
361
tation brings a mixture of common air and nitrous
air into much leſs compaſs than a mixture of
them without agitation. The difference is indeed
very great, and therefore ſhould always be men-
tioned. But in this caſe there was no proper agitation,
The fact above mentioned, I now conclude aroſe
from what remained of the nitrous air, not decom-
poſed in the mixture, being diminiſhed by paſſing
through ſo much ſpace of water, which is more ex-
poſed to its influence in a now than in a quick pal-
ſage. But I own I ſhould not have ſuſpected that
nitrous air would have been diminiſhed ſo very much
by being ſimply poured from one veſtel of water
into another, if I had not obſerved it in the follow-
ing manner.
Having mixed a quantity of air, which I knew
to be thoroughly phlogiſticated by the putrefaction
of fiſhes, with an equal quantity of nitrous air, I
transferred the mixture into my graduated tube ;
when, inſtead of occupying two whole meaſures,
as I had expected, they only occupied 1.95 mea-
fures. Suſpecting that the five hundred parts of a
meaſure which had diſappeared had been abſorbed
by the water, I poured the air back again into the
wide jar; and transferring it once more into the gra-
duated tube, found it to be only 1.8 meaſures ;
and pouring it about ten times backwards and for-
wards
362
Part II.
OBSERVATIONS ON
+
wards; without any unneceſſary agitation, it was re-
duced to 1.6. Having ſtood in water all night, I
meaſured it again the next morning, when I found
it to be 1.5; and by meaſuring three times more it
was reduced to 1.4.
I then poured two meaſures of nitrous air only
from the wide jar into the graduated tube, and
found that it was diminiſhed even in a greater pro-
portion than the former mixture.
In applying the teſt of nitrous air, I have lately
preferred equal meaſures of nitrous and of common
air, or of any air which may be conjectured a priori
to be nearly in the ſtate of common air, in order
that there might be phlogiſton enough to faturate it
entirely ; and if the remaining nitrous air was not
affected by water, this method would be perfectly
unexceptionable ; and with due precaution, it is
not liable to much objection. But the moſt accu-
rate method would be to uſe no more nitrous air
than the air to be examined is able completely to
decompoſe. But then it cannot be known before
hand how much this is. Perhaps, in order to guard
againſt the inconvenience above mentioned, it might
be moſt adviſeable, in common caſes, that is, when
the air to be examined is about the ſtandard of
common air, to uſe ſomething leſs than an equal
quantity of nitrous air, but more than one half,
which
Sect. I.
NITROUS AIR,
}
363
which was the quantity that I firſt confined my-
ſelf to.
I rather ſuſpect that when nitrous air is mixed
with common air, in a greater proportion than is
requiſite to the complete ſaturation of the common
air with phlogiſton, the fuperfluous nitrous air is
more diſpoſed to be abſorbed by-water than
pure
nitrous air. It appears, however, that, in no great
length of time, ſuch mixtures are brought to the
ſame dimenſions as if only half the quantity of ni-
trous air had been mixed with the common air.
This, I think, may be inferred from an experiment
which I made to try the difference between old and
freſh made nitrous air, both having been made in
the ſame manner, and, I believe, having been ori-
ginally of equal ſtrength.
October 25, 1777, I mixed equal quantities of
the ſame common air with equal quantities of the
old and freſh made nitrous air. What ſpace they
occupied at that time, and in ſeveral ſubſequent pe-
riods, is repreſented at one view, as follows:
With the old nitrous air. With the new
Oct. 27, 1777
1.05
Nov. 10,
1.07
0.93
0.96
0.86
Feb. 2, 1778,
0.84
0.8
The laſt is one fifth leſs than the original bulk
of the common air, and conſequently very near to
the
1
1.22
24,
A
364
OBSERVATIONS ON Part II.
the utmoſt limit of the diminution of common air
by any proper phlogiſtic proceſs. An accident prez
vented my obſerving this progreſs any farther.
SECTION. II.
Of the Impregnation of Water with nitrous Air.
HAV
AVING, among other kinds of air, expoſed
a quantity of nitrous air to water, out of
which all air had been well boiled, in the experi-
ment to which I may more than once refer (as
having been the occaſion of ſeveral new and impor-
tant obfervations) I found that ninetcen twentieths
of the whole was abſorbed. Perceiving, to my
great ſurprize, that ſo very great a proportion of this
kind of air was miſcible with water, I immediately
began to agitate a conſiderable quantity of it, in a
jar ſtanding in a trough of the ſame kind of water ;
and, with about four times as much agitation as
fixed air requires, it was fo far abſorbed by the wa-
ter, that only about one fifth remained. This re-
4
mainder
Sect. T.
NITROUS AIR.
365
mainder extinguiſhed Aame, and was noxious to
animals.
Afterwards I reduced a pretty large quantity
of nitrous air to one eighth of its original bulk, and
the remainder ſtill recained much of its peculiar
linell, and diminiſhed common air a little. A
mouſe alſo died in it, but not fo.ſuddenly as.it would
have done in pure nitrous: air. In this operation
the peculiar ſinell of nitrous air is very manifeſt,
the water being firſt impregnated with the air,
and then tranfmitting it to the common atmoſ.
phere.
This experiment gave me tlie hint of impreg-
nating water with nitrous air, in the manner in
which I had before done it with fixed air; and I
preſently, found that diſtilled water would imbibe
about one tenth of its bulk of this kind of air, and
that it acquiredla remarkably aſtringent taſte from
it. The finelliof water thus impregnated is at firſt
peculiarly pungent. I did not chuſe to ſwallow any
of it, though, for any thing that I know, it may
be perfectly innocent, and perhaps, in ſome caſes,
falutary-
This kind of air is retained very obſtinately by
water. In an exhauſted receiver a quantity of water
thus faturated emitted a whitiſh fume, ſuch as ſome
times iſſues from bubbles of this air when it is firſt
generated,
366
Part II.
OBSERVATIONS ON
generated, and alſo fome air-bubbles ; but though
it was ſuffered to ſtand a long time in this ſituation,
it ſtill retained its peculiar taſte ; but when it had
ſtood all night pretty near the fire, the water was
become quite vapid, and had depoſited a filmy kind
of matter, of which I had often collected a confider-
able quantity from the trough in which jars con-
taining this air had ſtood. This I ſuppoſe to be a
precipitate of the metal, by the ſolution of which
the nitrous air was generated. I have not given fo.
much attention to it as to know, with certainty,
in what circumſtances this depoſit is made, any more
than I do the matter depoſited from inflammable
air above-mentioned ; for I cannot get it, at leaſt
in any conſiderable quantity, when I pleaſe ; whereas
I have often found abundance of it, when I did not
expect it at all.
The nitrous air with which I made the firſt im-
pregnation of water was extracted from
copper;
but
when I made the impregnation with air from quick-
ſilver, the water had the very fame taſte, though
the matter depoſited from it ſeemed to be of a
different kind; for it was whitiſh, whereas the
other had a yellowiſh tinge. Except the firſt quan-
tity of this, impregnated water, I could never de-
prive any more that I made of its peculiar taſte.
I have even let ſome of it ſtand more than a week,
in
I
1
Sect. II.
NITROUS AIR.
367
in phials with their mouths open, and ſometimes
very near the fire, without producing any alteration
in it*
In the beginning of May 1776, I ſaturated a
quantity of diſtilled water with nitrous air produced
from biſmuth, and it happened to ſtand ten days,
or a fortnight, in the phial in which the impregnation
was made, the ſuperfluous nitrous air lying upon
the ſurface of it. Then, mindful of the caution
ſuggeſted by Mr. Bewly, not to admit the common
air to this nitrous air in contact with the water, I
very carefully, and as quickly as poſſible, ſlipped a
ſmall funnel into the mouth of the phial, in the in-
ſtant that I turned it upſide down ; and immediately
I filled it up with ſome of the water in the baſon in
which it had been inverted, ſo that the nitrous air,
in its eſcape mixed with the common air, and was
decompoſed, on the outſide of the phial, and not
within it. I have forgotten with what particular
view I had made this impregnation, but I had no
expectation of the reſult, cill, obſerving it the day
following, I found that it had depoſited a conſider-
able quantity of very white matter, and that the wa-
ter did not retain the leaſt ſenſible degree of acidity,
not even turning the juice of turnſole red. This
* I have ſince found, that nitrous air has never failed to eſcape
from the water, which has been impregnated with it, by long ex+
poſure to the open air.
experiment
368
Part II.
OBSERVATIONS O'N
experiment I have endeavoured to repeat, but al-
Ways
without ſucceſs.
At one time, in order to determine whether the
precipitate from water impregnated with nicrous air
was different according to the metal made uſe of in
procuring the air, I impregnated three quantities of
diſtilled water with nitrous air, of which one was
procured from biſmuth, another from copper, and a
third from iron, each in an eight ounce phial! In
all theſe caſes the water imbibed about one ſixth of
its bulk of this air ; and when the impregnation was
completed, I, as quickly as poſible, and in the
manner deſcribed in the laſt mentioned experiment,
filled all the phials with water from their reſpective
baſons. But very little depoſit was obfërved for a
conſiderable time, and the water in all the phialt
turned the juice of turnfold red. This iinpregna-
tion was made on the 28th of May, and the depoſit
having been made gradually, and as far as I could
obferve equally, the quantity of it was, in the be-
ginning of October, pretty confiderable"; but ſtiil
not more than half of wliar was depoſited' in the
firſt mentioned experiment. In all the phials;. aillo;
the colour of the depoſit was the fame, vizi a dark
brown. The water alſo in thein ail' was' full
acid, but not, I think, in ſo great a degree as ar
firt
Imagining
Sret: II.
NITROUS AIR.
369
İmagining that the difference might depend upon
the time that the ſuperfluous nitrous air had re-
mained upon the ſurface of the water (during which
I had never obſerved any depoſit to be made)
I let ſeveral of theſe impregnations remain a fort-
night; and ſome more than a month, before I in-
verted the phials; but ſtill the depoſit was made as
ſlowly as before, and was always of a browniſh co-
lour. In ſome caſes this depoſit was very incon
ſiderable.
When I heated this water, or when I put it into
an exhauſted receiver, and thereby expelled from it
all the air that I could, very little more depoſit was
made than there would have been if no air had
been extracted from it. Alſo whether the phials
containing the impregnated water were cloſely ſtop-
ped, or left quite open, there was no difference
with reſpect to the depoſit.
I imagined that I ſhould have procured a con-
fiderable quantity of this depoſit by decompoſing a
large quantity of nitrous air, which I did by means
of common air, in a ſmall quantity of water. Buc
though I repeated this proceſs till the water was be-
come exceedingly acid, it made no more depoſit
in a few days than would have been made from wa-
ter ſimply impregnated with nitrous air. One phial
of this water I put under an exhauſted receiver;
but though, by this means, a conſiderable quantity
VOL. I.
Вь
of
370
OBSERVATIONS ON Part II.
of air was diſcharged from it, it made no more de-
poſit than the reſt.
Imagining that the ccid which remained in this
water inight prevent the depoſit from being made,
eſpecially as in the firſt experiment, in which the
depoſit was ſo conſiderable, the water did not re-
tain any ſenſible acidity, I put a little cauſtic alkali
to the impregnated water ; but no viſible effect fol-
lowed from it. To prevent all acidity as much as
poſſible, I did not always depend upon my addreſs
in applying the funnel, in the manner deſcribed
above, but I let out the ſuperfluous nitrous air in a
trough of the fame water that had been impreg-
nated with it, ſo that it was impoffible for it to be
in the leaſt affected by the decompoſition of it with
the common air. But ſtill the reſult was not at all
different from what it had been in the other caſes in
which this precaution had not been taken.
Mr. Bewly has very well obſerved, that that aci-
dity of water iinpregnated with nitrous air which is
ſenſible to the taſte, is given to it by the decompoſition
of the nitrous air in contact with the impregnated
water ; but I have found, that a ſlight degree of
acidity, not indeed ſenſible to the taſte, but dif-
coverable by the juice of turnſole, is always com-
municated to water by its impregnation with nitrous
air. For if a phial be filled with water tinged blue
with the juice of turnſole, and then the nitrous air
be
.
4
Sext. II.
'371
NITROUS
AIR.
be admitted to it, and agitated in it, in order to pro-
mote the impregnation, a change of colour will
preſently be perceived in the water. But rain-water
ſo impregnated (the ſuperfluous air being let out un-
der water) retains ſo little acidity, as hardly to be diſ-
covered by mixing it with other water tinged blue.
I once imagined that nitrous air might poſſibly
undergo ſome change in its conftitution in conſe-
quence of its being imbibed by water; and for ſome
time I always expelled a proportion of fixed air along
with the nitrous, from water ſo impregnated; but
by uſing the following precaution I diſcovered my
miſtake. I carefully pumped all the air out of a
quantity of rain water, letting it ſtand twenty four
hours in a very good vacuum, and then impreg-
nated it with nitrous air ; when, immediately ex-
pelling all that I could of it by the heat of boiling
water, I found no part of it fixed air, but all pure
nitrous air, though not more than one fourth of the
quantity that had been imbibed by it.
I wiſh I could have given my reader more ſatiſ-
faction with reſpect to this depoſit made by nitroys
air ; but though I have given more attention to it
than perhaps to any other ſubject relating to air, I
have not. hitherto ſucceeded to my wiſh. Perhaps
I
may
be more fortunate hereafter. I have little
doubt, however, but that this precipitate conſiſts of
the calx of the metal, by the diffolution of which
the
B b 2
372
OBSERVATIONS ON Part II.
the nitrous air is procured, and the white colour of
the firſt depoſit from biſmuth may ariſe from a leſs
portion of phlogiſton adhering to it than to the
brown precipitates. But what I want is a method
of making the precipitate at pleaſure, that a quan-
tity might be procured for a careful examination,
and that the proportion of it, in a given quantity of
air, might be aſcertained.
SECTION III.
Of the Abſorption of nitrous Air by Oils, Spirit of Wine
and cauſtic Alkali.
ΤΗΣ
HAT water would imbibe a certain portion
of nitrous air, I diſcovered pretty early; but
that oils would do it, and eſpecially in ſuch a prodigi-
ous quantity, and ſo very rapidly, as I afterwards found
they do, I did not ſo much as ſuſpect at the time of
my laſt publication ; and the experiments will ſhew
that the decompoſition is effected by means of the
affinity which oils, and eſpecially the eſſential oils,
are known to have with the nitrous acid, or its baſe.
For
Seft, III.
NITROUS
373
AIR.
For it is evidently this part of the nitrous air that
they imbibe.
1
Having ſeen ſome reaſon to ſuſpect what would
be the conſequence of admitting nitrous air to oil
of turpentine, from what I had obſerved in my im-
pregnation of oils with the nitrous vapour, as will be
ſeen hereafter, I filled a ſmall glaſs jar with oil of
turpentine, inverted in a baſon of the fame ; and
on expelling that fluid by filling it with nitrous
air, I obſerved that, without any agitation, the ni-
trous air was diminiſhed ſo faſt, that in about fix
hours three fourths of it quite diſappeared. What
remained extinguiſhed a candle, being, in all re-
ſpects, the ſame with phlogiſticated air, or that to
which nitrous air is reduced by iron filings and
brimſtone, long agitation in water, and other pro-
ceſſes.
When I agitated nitrous air in oil of turpentine,
it was abſorbed quite as readily as fixed air is ab-
ſorbed by water ; but the quantity of nitrous air
that oil of turpentine will imbibe is vaſtly greater
than the quantity of fixed air that water can be made
to receive.
What is the limit in this caſe I cannot tell; but
throwing away the refiduum, which could not be
imbibed by oil of turpentine (which was generally
about one fourth of the whole, the ſame as in the
proceſs with iron filings and briinſtone) I made a
quantity
Bb 3
374
Part II.
OBSERVATIONS ON
quantity of this oil imbibe, at different times, eleven
times its bulk of nitrous air, and with very great
eaſe, even at the laſt; but not quite ſo readily as at
the firſt.
During this proceſs, the oil, from being tranſ-
parent, preſently became of a light orange colour,
and then had a yellowiſh caſt, and was a little glu-
tinous ; but towards the end of the proceſs part of
the oil became of a very deep orange, and, ſepa-
rating from the reft, funk to the bottom of the vef-
fel. It muſt have been the nitrous acid formed by the
nitrous air, and thc acidifying principle of pure air,
contained perhaps in the oil of turpentine ; and it
would probably have decompoſed more nitrous air,
till the whole of it had been converted into this
thick orange coloured maſs; which is the ſame
thing, as will be ſeen in its proper place, with
this oil after it has been fully impregnated with ni-
trous vapour.
I endeavoured to expel air from the oil of turpen-
tine which had imbibed ſuch a quantity of nitrous
air, but though I applied a conſiderable degree of
heat, no air came from it.
Willing to know the laſt ſtate to which the im-
pregnation with nitrous air would bring oil of tur-
pentine, I put a ſmall quantity of it into a thin
phial, ballancing it ſo that it would ſwim upright
in water, and then introduced it into a large jar of
nitrous
1
A
1
SeET. TIT.
375
NITROUS
AIR.
nitrous air ſtanding in water. It abforbed, in all,
two thirds of it; at firſt very ſlowiy, but afcerwards
more rapidly; the water riſing more in one day
than it had done in ſeveral days before, and the
whole proceſs laſted a week; after which part of
the oil of turpentine was become orange coloured
and thick, ſinking to the bottom of the phial, but
the change of colour was made at the ſurface. Af-
ter about ten days I took it out of this jar, and put
it into another jar of freſh nitrous air, when it began
to abſorb the air very faſt, having imbibed about
one fourth of it in one night.
Seeing no other appearance than the change of
the oil of turpentine into this dark orange coloured
maſs, I at length diſcontinued the proceſs, and ex-
poſed the ſubſtance I had procured to the open
air, when it became gradually thicker, till, in a
month or ſix weeks, it became almoſt as hard as
glue. The inſide of the jar in which this expe-
riment was made was nearly covered with ſmall
ſpecks of the fame glutinous orange coloured mat-
ter; the impregnated cil having, no doubt, been
exhaled, and having fettled on the ſides of the
glaſs, where, the more limpid part being evaporated,
the reſt became of the conſiſtence above men-
tioned.
I alſo made a quantity of oil of turpentine im-
bibe nitrous acid from nitrous air, by faturating
with
Bb 4
376
Part II.
OBSERVATIONS ON
with it the common air in the phial in which it
was contained.
It preſently became very hot;
was firſt green, and then of an orange colour, and
parts of it becoming very thick and glutinous,
ſunk to the bottom, exactly as the oil of turpentine
which had imbibed the nitrous air in the preceding
proceſs, or the nitrous vapour.
N. B. After I
had made ſome progreſs in this operation, it went
on very rapidly. For immediately after I had ap-
plied the bladder of nitrous air to the phial, it
ruſhed into it, and all the nitrous air was decom-
poſed in a few ſeconds. In this circumſtance, alſo, '
there is a remarkable reſemblance between the
two proceſſes; the decompoſition of the nitrouş
air in both caſes not having been effected ſo rapidly
at the firſt, as ſome time afterwards.
Ether has the ſame power of abſorbing nitrous
air that oil of turpentine pofſeffes. Having filled
a phial with ether, and inverted it in a baſon of the
fame, I introduced a quantity of nitrous air into it,
in the ſame manner as I had done to the oil of
turpentine; and preſently found that, with a very
little agitation, three fourths of it diſappeared, and
the remainder poffeſfed no nitrous property.
Willing to ſee the whole effect of nitrous air
upon ether, I introduced a ſmall quantity of it into
a large jar of nitrous air, in the fame manner as
I had done with oil of curpentine in the above-
mentioned
Segt. III.
377
NITROUS AIR.
mentioned experiment. For ſeveral days air kept
bubbling out at the bottom of the jar (the effect
of ether on all kinds of air, as I have ob-
ferved, being to increaſe, and almoſt double the
whole quantity of it) but after this time the air in
the jar began to be diminiſhed, and the water to
riſe in it, the phial containing the ether always
ſwimming on its ſurface. But at the end of the
proceſs, which continued about three weeks, one
third of the air in the jar remained. After this I
perceived no alteration in its quantity: but, letting
it remain a fortnight longer, I examined it, and
found the ether very much diminiſhed in quantity,
though not changed in its appearance; but it did
not evaporate on being expoſed to the open air
as ether does. What was inoſt remarkable was,
that the nitrous air had loſt hardly any thing of
its peculiar property of diminiſhing common air.
But it may be ſuppoſed that there was not a quantity
of ether ſufficient to produce any conſiderable
change in ſo large a quantity of nitrous air; and
the reaſon why what remained of the ether, after
this experiment, did not evaporate, might be, that
the exhalation of the water within the jar had mix-
ed with it, and diluted it very much.
Olive oil, likewiſe, imbibes nitrous air, but not
rapidly, perhaps about half as faſt as water imbibes
fixed air without agitation; which makes very
little
378
Part II.
OBSERVATIONS ON
little difference in the caſe of oil, on account of its
viſcidity, and conſequently its not being much
divided by that operation. By long ſtanding, a
quantity of olive oil imbibed almoſt the whole of a
ſinall quantity of nitrous air.
Olive oil, by which a quantity of nitrous air had
been confined in a phial ſeveral months, had ab-
forbed almoſt the whole of it, and that part of the
oil which was contiguous to the air was coagulated
in lumps, as if it had been frozen, and remained
a long time at the top of the oil. But afterwards,
being looſened, I ſuppoſe, by the warmth of the
weather, it all funk to the bottom, as the ice of oil
always does.
This property of diminiſhing nitrous air, is not
peculiar to oils.
It is likewiſe found in cauſtic
alkali, though not in the ſame degree. Imagining
that the preceding oils ſeized upon the acid of
nitrous air, and thereby decompoſed it, I thought
that alkalies, having the ſtrongeſt affinity with acids,
cauſtic alkaline liquors, fixed and volatile, muſt
have the ſame effect; and the experiments ſeemed
to verify my conjecture. Having put a quantity
of nitrous air to a phial of cauſtic fixed alkali, im-
merſed in a baſon of the ſaine, I obſerved that,
in the ſpace of three days, and without agitation,
ſo much of it had been abſorbed, that not more
than one fixth of the quantity remained, and after
ſix
1
Sect. III.
379
NITROUS AIR.
ſix days about one twelfth part of it only was
left.
An equal quantity of volatile alkali, in ſimilar
circumſtances, imbibed, at the ſame time, but little
of the nitrous air. But at another time, after
waiting about a week, I obſerved that a quantity
of it had abſorbed about one third of a ſmall
quantity of nitrous air that had refted upon its
ſürſace.
At another time I obſerved that a quantity of
fixed alkali abſorbed almoſt the whole of about
one fourth of its bulk of nitrous air ; for the re-
mainder could not be more than one twentieth
part. But when a phial was quite filled with ni-
trous air, and placed with its mouth in a baſon
of the fame Auid, the abſorption went on very
flowly.
When, by means of agitation, I had made a
quantity of fixed cauſtic alkali imbibe its bulk of
nitrous air, I obſerved that the colour of it was
not in the leaſt ſenſibly changed; alſo it had no
more effect upon iron than it had before this proceſs.
Cauſtic alkali had no ſenſible effect either on
common or inflammable air, though only a ſmall
quantity of theſe kinds of air was kept in con-
tact with a large quantity of this liquor about a
week.
At the ſame time that I firſt expoſed nitrous
air to oil of turpentine, I, in the ſaine manner,
brought
380
OBSERVATIONS ON Part II.
brought it into contact with ſpirit of wine ; and ac-
that time the abſorption, without agitation, ſeemed
to be almoſt as conſiderable as that with the oil of
turpentine. But though this fluid imbibed the ni-
trous air
very
faſt at the firſt, it was foon faturated,
which is not the caſe with oil of turpentine, By
repeating the proceſs ſeveral times, I made a
quantity of ſpirit of wine imbibe its bulk of ni-
trous air.
But after this it received more air
with great difficulty; and though I did not urge
it to the utmoſt, I do not think that it would
have taken much more. No change was produced
in the appearance of the ſpirit of wine, it being as
tranſparent as at firſt; and, what I thought a little
remarkable, it did not affect the juice of turnſole
in any other manner than ſpirit of wine always
does. The application of beat to the ſpirit of wine
thus impregnated did not expel any air from it,
any more than it had done from the oil of turpen-
tine impregnated in the ſame manner.
In order to compare the abſorption of nitrous
air by ſpirit of wine and by oil of turpentine, I
filled two cylindrical glaſs veſſels, nine inches in
length, one with oil of turpentine, and the other
with ſpirit of wine, inverting them in baſons of the
ſame. Then, expelling the liquors, I filled them
both completely with nitrous air, and obſerved that
in leſs than a day the oil of turpentine had ab-
forbed three fourths of its air, while the ſpirit of
wine
Sect. IV.
NITROUS AIR.
381
wine had not riſen in the jar more than three
quarters of an inch, and it never advanced any
higher.
SECTION
IV.
Of the Phenomena attending the Abſorption of nitrous
Air by acid Liquors.
A
S nitrous air is liable to be decompoſed by
any ſubſtance that has a near affinity either
with its phlogiſton, or with any other of its con-
ſtituent parts, it was natural to think of trying the
effect of the ſeveral acids, which are known to
have a conſiderable affinity with phlogiſton. Ach
cordingly, about the ſame time that I made the
experiments deſcribed in the laſt ſection, I con-
veyed a quantity of nitrous air into phials previouſly
filled with the vitriolic, nitrous and marine acids; and
it preſently appeared that all of them got phlo-
giſton from this air; but the quantity of it which
the nitrous acid decompoſed, the quickneſs of the
proceſs, and the effect of it upon the nitrous acid
itſelf,
382
OBSERVATIONS ON Part II
itſelf, were appearances that I viewed with aſtoniſh-
ment, having had no expectation of any ſuch reſult ;
and ſeveral good chemiſts of my acquaintance have
expreſſed no leſs ſurprize at them than myſelf,
though theſe facts will appear leſs extraordinary,
when it is conſidered how very ſtrong is the affinity
between this acid and phlogiſton. This, how-
ever, is perhaps a more evident proof of the pecu-
liar ſtrength of this affinity than any other fact
that chemiſtry has hitherto furniſhed.
Having, in all the other caſes, had occaſion to
agitate this ſpecies of air in the Auids which I
expected to abſorb it; the moment that I intro-
duced this air to the nitrous acid, I was, as uſual,
beginning to agitate it; but with the leaſt moţion
the abſorption was almoſt inſtantaneous, being nearly
as quick as the abſorption of acid or alkaline air
water ; and the quantity of nitrous air that a
very ſmall proportion of this acid is able to de-
.compoſe, and to appearance abſorb, almoſt exceeds
belief.
Finding this abſorption ſo very rapid, I had no
occaſion to introduce the air into phials previoully
filled with nitrous acid, in the manner in which I
had done with reſpect to other Auids, but only
filled the phials with nitrous air, and covering the
mouths of them with my finger, placed them in-
verted in a baſon of the acid; when the abſorption
would
Selt. IV
383
NITROUS AIR.
would inſtantly commence, and the fluid, without
any agitation, would riſe gradually and viſibly, till the
greateſt part of the air diſappeared. Making the
experiments in this manner, I obſerved that the
upper part of the acid, on which the nitrous air
reſted, became firſt of a deep orange, and then of
a green colour.
to get into it.
In order to obſerve the full effect of nitrous air
on a given quantity of ſtrong nitrous acid, I filled
a ſmall phial with it, and then introduced it through
the water into a large jar previouſly filled with
nitrous air, and ſupported the phial in ſuch a man-
ner, as that the water could never riſe fo high as
into it. In theſe circumſtances, the ſurface
of the liqour, which was at firſt of a pale yellow,
preſently aſſumed a deep orange colour, and the
quantity of air abſorbed was indeed very great.
I was ſo much Itruck with this experiment, that
I repeated it very often; and the following is a
diſtinct recital of all the remarkable appearances
attending one of them, which I felect from the
reſt, as I noted them more minutely than in any
other proceſs of the kind.
Having filled a phial, containing exactly the
quantity of four pennyweights of water, with a
ſtrong pale yellow ſpirit of nitre, with its mouth
quite cloſe to the top of a pretty large receiver,
ſtanding in water, I carefully drew out almoſt all
the
1
1
384
OBSERVATIONS ON Part II.
the common air, and then filled it with nitrou.
air; and as this was abſorbed, I kept putting is
more, till, in leſs than two days, it had completely
abſorbed 130 ounce meaſures.
Preſently after this proceſs began, the ſurface
of the acid aſſumed a deep orange colour, and
when twenty or thirty ounce meaſures of air were
abſorbed, it began to be ſenſibly green at the top;
and this green kept deſcending lower and lower,
till it reached the bottom of the phial. Towards
the end of the proceſs, the evaporation of the acid
was perceived to be very great; and when I took
it out, the quantity was found to have been dimi-
niſhed exactly one half: for there remained no
more than the quantity of two pennyweights of
Alſo it had become, by means of this
proceſs and the evaporation together, exceedingly,
weak, and was rather blue than green.
The phial of ſpirit of nitre in this experiment
was ſupported by an iron wire, riſing from a fac
piece of braſs; and having at one time filled the
receiver quite full of nitrous air, ſo as to leave
the whole ſtand quite bare, I obſerved that great
quantities of air iſſued from them, the moiſture
on their ſurface rendering this effect very apparent.
This muſt have been an additional quantity of ni-
trous air, produced by the nitrous vapour which
had been exhaled from the phial, or depoſited in
water.
I
the
Sect. IV. NITROUS AIR.
385
I
the decompoſition of the nitrous air, and muſt be
conſidered as having been abſorbed by the acid in
the phial, beſides that which I threw into it. How
much was the amount of this additional quantity
of nitrous air, decompoſed by the acid in the phial,
I cannot certainly tell ; but ſhould gueſs, from the
circumſtances, that it could not be leſs than twenty
ounce meaſures; which, added to the 130 above:
mentioned, makes the whole quantity abſorbed to
have been 150 ounce meaſures. Beſides, I. wich-
drew the phial before the abſorption had quite
ceaſed.
At another time I was determined that the ni.
trous acid ſhould continue in nitrous air till it could
not poſſibly abforb any more of it, in order to
obſerve what the acid itſelf would become after
being fully ſaturated with phlogiſton in this man-
ner, and when it had at the ſame time exhaled
as much as it could of its own acid in thoſe cir-
cumſtances. The conſequence was, that, in four
or five days, when the proceſs terminated, the acid
was become of a very light blue colour, and, as in the
former caſe, was reduced to half its dimenſions ;
ſo that the evaporation of the acid in this confined
ſituation ceaſes before it becomes quite tranſparent,
as it does by long expoſure to the open air, though
it is very poſſible, that a much longer continuance,
VOL. I.
Сс
even
I
1
386
OBSERVATIONS ON
Part II.
even in theſe circumſtances, would have the ſame
cffeet.
The above-mentioned experiments were made
with the ſtrongeſt yellow ſpirit of nitre. When I
expoſed to the nitrous air a quantity of blue ſpirit
of nitre, the air was abſorbed, but by no means in
ſo great a quantity as by the other acid; and the
ſurface of this acid became of a deeper blue in
theſe circumſtances. Had it been continued longer,
it would, I ſuppoſe, have returned to a lighter
blue by the evaporation of its acid; in which ſtate
it would have loſt its power of attracting phlogiſ-
ton from the nitrous air, as in the laſt-mentioned
experiment. The nitrous air which had been ex-
poſed to this blue ſpirit of nitre was diminiſhed a
little by freſh nitrous air.
Having obſerved the change that took place in
nitrous air by means of ſpirit of nitre, I was de-
ſirous of knowing whether the ſpirit of nitre in
which it was agitated acquired or loſt ſtrength;
when I foon found that, in conſequence of getting
more phlogiſton, its power of diffolving metals
was diminiſhed, though it will be ſeen that the
acid muſt have been weakened a little in the courſe
of the experiment.
In order to effect my purpoſe, I firſt .filled a
phial with the nitrous acid, which was very ſtrong,
and
Sect. IV.
NITROUS AIR.
387
and of a pale yellow colour; and placing it invert-
ed in a baſon of the fame, I introduced to it, by
means of a bladder, a quantity of nitrous air; and
when the acid had abſorbed as much as it could
of this, I threw out the reſiduum of phlogiſticated
air, and filling it up again with ſpirit of nitre from
the ſame baſon, I fupplied it with more nitrous
air.
This I continued to do for a conſiderable time,
and obſerved that by the proceſs the acid became very
brown, and ſmoking; in conſequence, no doubt,
of having acquired phlogiſton from the nitrous air.
In diſſolving copper with this acid, immediately
after the proceſs, I found that it was become weaker
in the proportion of five and a half to ſeven. It
muſt be obſerved, however, that the evaporation
during the proceſs (though I made it as expedi-
tiouſly as I poſſibly could) muſt have weakened
the acid a little, and alſo the end of a wet glaſs
tube (though I never failed to wipe it as well as
I could) being dipped into it every time that I
fupplied it with more air, muſt have diluted it a
little more.
Obſerving the readineſs with which nitrous acid
decompoſed nitrous air, by depriving it of its phlo-
giſton, I had the curioſity to try how far the agi-
tation of a quantity of this air in ſtrong fpirit of
nitre would depurate it; and it was not without
ſurprize
Cc 2
388
Part II.
OBSERVATIONS
ON
ſurprize that I found that, when this proceſs had
continued but a very ſhort time, the air had be-
come ſo far pure by the loſs of its phlogiſton;
that two meaſures of it and one of freſh nitrous
air occupied the ſpace of two meaſures and two
thirds. I then tried the effect of this proceſs
on air phlogiſticated by nitrous air, and found
that this alſo was conſiderably improved by this
means.
In both theſe caſes the air was far from being
ſo pure as to be fit for reſpiration; but that
any kind of air fhould be reduced by this proceſs
to a ſtate that is at all better than perfectly phlo-
giſticated, will appear extraordinary, when it is
conſidered, that, notwithſtanding the affinity there
is between this acid and phlogiſton, yet that the
vapour
of it never fails to impart phlogiſton to
common air, ſo as to deprave it conſiderably. In
ſeveral cafes I have obſerved that common air
thus expoſed to the influence of nitrous vapour
has become perfectly phlogiſticated in a very ſhort
ſpace of time. It ſhould ſeem that the nitrous
acid, when combined with water, has a ſtronger
affinity with phlogiſton than it retains in the form
of vapour, free from water.
The effect of oil of vitriol, and ſpirit of ſalt,
on nitrous air is by no means fo remarkable as
the effect of the nitrous acid upon it; but it is
fufficiently
1
1
SéET. IV.
NITROUS AIR.
389
fufficiently evident that both theſe mineral acids
do really decompoſe this air in part; and the im-
pregnation they receive from the phlogiſton they
take from it is worth notice.
Oil of vitriol imbibes almoſt as much nitrous
air as water can do, and requires about the ſame
degree of agitation, or rather more, to effect it.
Two thirds of the quantity of the air admitted
to about four times as much of the acid was im-
bibed, and the oil of vitriol, which was before
quite colourleſs, aſſumed a beautiful purple hue.
Spirit of ſalt imbibes nitrous air very Nowly,
and in a ſmall quantity ; but by this ſmall impreg-
nation, from being of a light ſtraw colour, it be-
came of a beautiful ſky blue, very viſible when
held up to the light. The quantity abſorbed was
about one twentieth of its own bulk, and one
third of the nitrous air employed in the experiment.
In order to obſerve what proportion of nitrous air
a quantity of ſpirit of falt would abſorb with long
ſtanding, I ſuffered thein to continue in contact
in one cafe about two months; and after that time
about two thirds of the air, which was originally
about one fourth of the bulk of acid, was imbibed;
and I imagine that with more time, ſtill more of
the air will diſappear.
Nitrous air was readily abſorbed without agita-
tion by water impregnated both with vitriolic acid
air
Сс 3
390
Part 11.
OBSERVATIONS ON
1
air and fluor acid air. Each took more than its
bulk, and not more than one twentieth part of the ni-
trous air remained unabſorbed. How much more
would have been abſorbed I did not try. No
change of colour was produced by the proceſs.
N. B. Agitation only ſet looſe the vapour of theſe
acid liquors, and thereby increaſed the apparent
bulk of the air. Theſe two kinds of acid air im-
bibing nitrous air in the fame manner is an argu-
ment for their being ultimately the ſame thing.
Both radical vinegar, and concentrated vegetable acid,
abſorbed nitrous air conſiderably faſter than water.
Of theſe acid liquors the former retained its trans-
parency; for though, during the agitation it ſud-
denly became of a turbid white, that change took
place on the accidental admiſſion of a bubble or
two of common air, though I do not underſtand
how this circumſtance could produce that effect.
The concentrated vegetable acid aſſumed a dark
pur-
ple in conſequence of this impregnation, very much
reſembling the oil of vitriol after the ſame proceſs.
SEC-
i
!
SET. V.
391
NITROUS AIR,
SECTION
V.
Of the antiſeptic Power of nitrous Air.
1
I!
T will perhaps be thought, that the moſt uſeful,
if not the moſt remarkable, of all the properties
of this extraordinary kind of air, is its power of
preſerving animal ſubſtances from putrefaction, and
of reſtoring thoſe that are already putrid, which it
poſſeſſes in a far greater degree than fixed air. My
firſt obſervation of this was altogether caſual.
Having found nitrous air to ſuffer ſo great a di-
minution by a mixture of iron filings and brim-
ſtone, I was willing to try whether it would be
equally diminiſhed by other cauſes of the diminu-
tion of common air, eſpecially by putrefaction ;
and for this purpoſe I put a dead mouſe into a
quantity of it, and placed it near the fire, where
the tendency to putrefaction was very great. In
this caſe there was a conſiderable diminution, viz.
from five and a quarter to three and a quarter ;
but not ſo great as I had expected, the antiſeptic
power of the nitrous air having checked the ten-
dency to putrefaction; for when, after a week, I
took
Сс 4
392
OBSERVATIONS ON Part II.
took the mouſe out, I perceived, to my very great
ſurprize, that it had no offenſive ſmell.
Upon this I took two other mice, one of them
juſt killed, and the other ſoft and putrid, and put
them both into the fame jar of nitrous air, ſtand-
ing in the uſual temperature of the weather, in the
months of July and Auguſt of 1772; and after
twenty five days, having obſerved that there was
little or no change in the quantity of the air, I
took the mice out; and, examining them, found
them both perfectly ſweet, even when cut through
in ſeveral places. That which had been put into
the air when juſt dead was quite firm; and the
fleſh of the other, which had been putrid and ſoft,
was ſtill ſoft, but perfectly ſweet.
In order to compare the antiſeptic power of
this kind of air with that of fixed air, I examined
a mouſe which I had incloſed in a phial full of fixed
air, as pure as I could make it, and which I had
corked very cloſe. But upon opening this phial
in water about a month after, I perceived that a
large quantity of putrid effluvium had been gene-
rated; for it ruſhed with violence out of the phial;
and the ſmell that came from it, the moment the
cork was taken out, was inſufferably offenſive. In-
deed Dr. Macbride fays, that he could only reſtore
very
thin pieces of putrid fleſh by means of fixed
air
I once
1
+
1
Seet. V.
NITROUS AIR.
393
I once thought that if a little pains were taken
with this ſubject, this remarkable antiſeptic power
of nitrous air might poſſibly be applied to various
uſes, perhaps to the preſervation of the more deli-
cate birds, fiſhes, fruits, &c. mixing it in different
proportions with common or fixed air, and eſpeci-
ally that anatomiſts might perhaps avail themſelves
of it; but Mr. Hey, who made the trial, found
that, after ſome months, various animal ſubſtances
were ſhriveled, and did not preſerve their natural
forms in this kind of air.
I have made a few experiments, in order to aſcer-
tain whether it be poſſible to derive any advantage
from this property of nitrous air for culinary pur-
pojës. But I cannot ſay that my obſervations have
been very favourable to it in this reſpect. Nitrous
air will, indeed, preſerve Aeſh meat from putre-
faction; but after long keeping in this manner it
becomes very offenſive, both to the noſtrils, and the
palate, though the ſmell is not altogether that of
putrefaction ; and indeed the ſubſtance continuing
quite firm, it could not be properly putrid. Though
theſe experiments were not quite fair, becauſe the
nitrous air had not been renewed ſo often as it ought
to have been, ſeveral of the phenomena may be
worth mentioning.
On the 28th of April 1777, I put two pigeons
into two jars of nitrous air, juſt wide enough to
contain
1
394
Part II.
OBSERVATIONS ON
contain them, with about as much nitrous air in
the jars, as the bulk of the pigeons. From this
time till the 4th of June following, I had renewed
the nitrous air but once, and then, taking them out,
I found them both free from all ſmell of
putre-
faction. One of them was broiled, when the fleſh
was found to be ſweet, but it had not the natural
taſte of the pigeon, and was, on the whole, unplea-
fant. The fleſh was quite red throughout, and a
little harder than that of a pigeon generally is. The
water contained in the cups, in which the jars with
the pigeons had ſtood, had generally been very of-
fenſive, ſo that it ſhould ſeem that the putrid effiu-
vium (containing, probably, much phlogiſton, and
perhaps the moſt nutritive part of the Aeſh) had
paſſed through the nitrous air, and the water, into
the ſurrounding atmoſphere.
I replaced the pigeon that was not uſed, and let
it remain, along with two others which had been
kept the fame time, till the 13th of September fol-
lowing, in all, near ſix months, or the whole fum-
mer feaſon ; but I had not been careful to change
the air very often, though I did it two days before
I took them out the laſt time. The pigeons had
now certainly a very bad ſmell, though their fleſh
was firm, and ſo were even the bowels of one of
them which had not been drawn. When they were
dreiled, they were much more offenſive, and had a
ſtrong
Seet. V.
395
NITROUS AIR.
ſtrong ſmell of putrefaction, or ſomething very much
reſembling it. The fleſh was red throughout, ſtill
firm, and excluſive of the ſmell, had little or no
taſte. My friend, Mr. Magellan, who was with me
at the preparation of them, had not ſo bad an opi-
nion of this piece of cookery as I had.
On the roth of May I put into a jar of nitrous
air a large wood pigeon; and taking it out on the
18th of June following, obſerved that it had a ſtrong
and offenſive ſmell, but the fleſh was perfectly firm.
Though a very great part of the air had been ab-
forbed, and during the fortnight preceding the exa-
mination it had not been ſupplied with freſh air,
as it had been occaſionally before, the air to which
it had been expoſed all that time diminiſhed com-
mon air quite as much as freſh made nitrous air.
It was this obſervation that gave me the firſt fuf-
picion of the manner in which nitrous air is dimi-
niſhed in this and in other proceſſes. Having re-
placed the pigeon in the jar, I found on the 7th of
Auguſt following, that the air was but ſlightly ni-
trous, and on the 22d of the ſame month it was
mere phlogiſticated air. After this I neglected to
attend to it, and at laſt threw it away. Whether,
in this proceſs, the nitrous air ever comes into a ſtate
in which a candle will burn in it, or not, I cannot
tell. The experiment is a very unpleaſant one, and
I ſhall hardly repeat it.
I
In.
396
OBSERVATIONS ON
Part II:
In all theſe caſes the fleſh was kept a long time,
viz. through the ſix ſummer months ; and though
nitrous air failed to preſerve meat in a ſtate fic for
eating ſo very long, it may poſſibly anſwer the pur-
poſe for a few days tolerably well, as it will certainly
reſtore meat that has begun to turn putrid. One
trial of this kind I did make.
On the 14th of June 1777, I took a fowl which
had been killed a week, and which had been pur-
poſely kept till it was offenſive; and putting it into
jar of nitrous air, obſerved that the air began im-
mediately to be abſorbed, and on the 16th I took
the fowl out, when it had no ſmell of putrefaction:
at all; but when it was boiled, though myſelf and
ſeveral other perfons tafted of it, and perceived no-
thing diſagreeable in the taſte itſelf, we were dif-
guſted with a faint ſmell that came from the body
of the fowl, when we held it to our noſtrils. Per-
haps it had not been expoſed to the nitrous air quite
long enough.
Though part of this air had been abſorbed, the
remainder diminiſhed common air quite as much as
any freſh made nitrous air.
On the ſubject of this ſection I ſhall obſerve that
Dr. Millman having been ſo obliging as to inform
me that he had found that bile is prevented from
becoming putrid much longer by being impregnated
with fixed air, than it could otherwiſe be; I was.
deſirous
Seet. V.
397
NITROUS AIR.
.
:
deſirous of trying what effect the impregnation with
nitrous air would have upon it. Accordingly, on
the 19th of February 1777, I impregnated a quan-
tity of ox bile, with which he ſupplied me with
nitrous air ; when, from being viſcid, it preſently
became limpid like water, and aſſumed a browniſh
hue, without depoſiting any thing that I could per-
ceive. This bile continued perfectly ſweet till the
the 20th of March following, when it was packed
up, along with other things, and removed from
London into the country. Examining it fo time
afterwards, I found it had contracted a ſmell of
pu-
trefaction, and on the 23d of April, it was quite
putrid. The ſame brown colour continued, but
it had depoſited ſomething of a whitiſh colour.
!
+
SEC.
398
Part II.
OBSERVATIONS ON
SECTION VI.
Of the Formation of nitrous Ammoniac by nitrous Air.
1
1
In
N the mixture of this kind of air with common
air, in a trough of water which had been putrid,
but which at that time ſeemed to have recovered its
former ſweetneſs (for it was not in the leaſt degree
offenſive to the ſmell) a phenomenon ſometimes
occurred, which for a long time exceedingly de-
lighted and puzzled me.
When the diminution of the air was nearly com-
pleted, the veſſel in which the mixture was made
began to be filled with the moſt beautiful white
fumes, exactly reſembling the precipitation of fome
white ſubſtance in a tranſparent menftruum, or the
falling of very fine ſnow; except that it was much
thicker below than above, as indeed is the caſe in
all chemical precipitations. This appearance conti-
nued two or three ininutes.
Afterwards, having (with a view to obſerve whe-
ther any cryſtals would be formed by the union of
volatile alkali, and nitrous air, ſimilar to thoſe form-
ed by it and fixed air, as deſcribed by Mr. Smech
in his Diſſertation on fixed Air) opened the mouth
of
1
Seet. VI.
399
NITROUS AIR.
1
of a phial which was half filled with a volatile alka-
line liquor, in a jar of nitrous air, 1 had an appear-
ance which perfectly explained the preceding. All
that
part
of the phial which was above the liquors
and which contained common air, was filled with
beautiful white clouds, as if ſome fine white powder
had been inſtantly thrown into it, and ſome of theſe
clouds roſe within the jar of nitrous air. This ap-
pearance continued about a minute, and then intirely
diſappeared, the air becoming tranſparent.
Withdrawing the phial, and expoſing it to the
common air, it there alſo became turbid, and foon
after the tranſparency returned. Introducing it
again into the nitrous air, the clouds appeared as
before. In this manner the white fumes and tranſ-
parency
ſucceeded each other alternately, as often
as I choſe to repeat the experiment, and would, no
doubt, have continued till the air in the jar had been
thoroughly diluted with cominon air. Theſe ap-
pearances were the fanie with any ſubſtance that
contained volatile alkali, fluid or folid.
When, inſtead of the finall phial, I uſed a large
and tall glaſs jar, this appearance was truly fine and
ſtriking, eſpecially when the water in the trough was
very tranſparent. For I had only to put the ſmall-
eſt drop of a volatile alkaline liquor, or the ſmalleſt
bit of the ſolid ſalt, into the jar, and the moment
that the mouth of it was opened in a jar of nitrous
air,
1
400
Part II.
OBSERVATIONS ON
air, the white clouds above mentioned began to be
formed at the mouth, and preſently deſcended to
the bottom, ſo as to fill the whole, were it ever ſo
large, as with fine ſnow.
In conſidering this experiment, I ſoon perceived
that this curious appearance muſt have been occa-
ſioned by the mixture of the nitrous and common
air, and therefore that the white clouds muſt be
nitrous ammoniac, formed by the acid of the nitrous
air, ſet looſe in the decompoſition of it by common
air, while the phlogiſton, which muſt be another
conftituent
part
of nitrous air, entering the common
air, is the cauſe of the diminution it ſuffers in this
proceſs ; as it is the cauſe of a ſimilar diminution,
in a variety of other proceſſes.
In diverſifying this experiment, I found that it
appeared to very great advantage when I ſuſpended
a piece of volatile ſalt in the common air, previous
to the admiſſion of nitrous air to it, incloſing it in
a bit of gauze, muſlin, or a ſmall net of wire. For,
preſently after the redneſs of the mixture begins to
go off, the white cloud, like ſnow, begins to de-
ſcend from the ſalt, as if a white powder was ſhaken
out of the bag that contains it. This white cloud
preſently fills the whole veſſel, and the appearance
will laſt about five minutes.
If the falt be not put to the mixture of theſe two
kinds of air till it has perfectly recovered its tranſ-
parency,
Saat. VI.
401
NITROUS AIR.
.
1
Jl
1
parency, the efferveſcence being completely over,
no white cloud will be formed ; and, what is rather
more remarkable, there is nothing of this appear-
ance when the falt is put into the nitrous air itſelf.
The reaſon of this muſt be, that till common air
be admitted to the nitrous, no acid is formed, to
unite with the alkali, and make the nitrous am-
moniac.
Having generally faſtened the ſmall bag which
contained the volatile falt to a piece of braſs wire in
the preceding experiment, I commonly found the
end of it corroded, and covered with a blue fub-
ſtance. Alſo the falt itſelf, and ſometimes the bag
was dyed blue. But finding that this was not the
cafe when I uſed an iron wire in the ſame circum-
ſtances, but that it became red, I was ſatisfied that
both the metals had been diſſolved by the volatile
alkali, or the acid. At firſt I had a fufpicion that the
blue might have come from the copper, out of which
the nitrous air had been made. But when the hi-
trous air was made from iron, the appearances were,
in all reſpects the ſame.
Vol. I.
Dd
SEC-
.
402
Part II
OBSERVATIONS ON
.
SECTION VII.
Explanation of fome Phenomena attending the Solutiot
of Metals in nitrous Acid.
AS
S the diſcovery of fixed air in calcareous ſub-
ſtances threw new light upon many pheno-
mena in chemiſtry, in like manner the diſcovery of
every other kind of air, and indeed of every proper-
ty of any of them, muſt throw light upon thoſe
proceſſes in which they are concerned. Not being
a profeſſed chemiſt, and attending only to ſuch ar-
ticles in that branch of knowledge as my own pur-
ſuits are particularly connected with (though theſe
neceſſarily grow more various and extenſive conti-
nually) ſuch illuſtrations of chemical proceſſes are
not ſo likely to occur to me, as they are to others,
who by their profeſſion give a general attention to
every thing within the whole compaſs of chemiſtry.
Such, however, as I have had occaſion to attend to,
and which I imagine I can throw any light upon,
I
ſhall not fail to mention.
There
SeEt. VII.
403
NITROUS AIR.
There are many facts relating to the ſolution of
metals in ſpirit of nitre, which could not have been
underſtood without the knowledge of nitrous air ;
and yet, though ſeveral of them are very remark-
able, I do not find that even the phenomena them-
ſelves, and much leſs the difficulties attending the ,
ſolution of them, have been ſo much as noticed.
I am perſuaded, however, that an attention to the
nature of this remarkable kind of air will contribute
greatly to the inveſtigation of the conſtitution of
the ſeveral metals, and the explanation of many
phenomena attending their decompoſition, and con-
ſequently their compoſition.
Having had frequent occaſion to diffolve mer-
cury in ſtrong ſpirit of nitre, in order to procure
from it nitrous and dephlogiſticated air, and to note
the quantity of the metal revivified afterwards, I
could not help being very particularly ſtruck with
ſome phenomena in the ſolution, which are as fol-
lows.
The moment that ſtrong ſpirit of nitre is poured
upon quickſilver, the ſolution is inſtantly very rapid.
But though it is known that one method of procur-
ing nitrous air is by the ſolution of this metal in the
nitrous acid, not a ſingle bubble of any kind of air
is ſeen to be formed; at leaſt none rifes through the
acid. Preſently, however, one may perceive, that
very
Od 2
404
Part II.
OBSERVATIONS ON
th
very large bubbles of air are formed, but they in-
ſtantly diſappear, and nothing remains of them but
the ſmalleſt ſpecks imaginable, to riſe to the top of
the acid, By degrees, the acid near the mercury
becomes of a deep orange colour, and then through
this part of the acid the bubbles of air aſcend freely;
but the moment they come to the ſuperincumbent
pale coloured acid, they collapſe into thoſe ſmall
and barely perceivable points, yielding no air that
can be collected in any ſenſible quantity. And it is
not till the whole quantity of the acid is changed
from a pale to an orange colour, that any nitrous
air can be collected. Then, however, the bubbles
riſe freely to the top of the acid, and, mixing with
the incumbent common air, exhibit an orange co-
lour by their decompoſition on mixing with it.
Then, alſo, a ſtrong ſmell of ſpirit of nitre is per-
ceived, as it always happens when nitrous air is let
looſe to mix with the air of the room in which we
are breathing. Whereas, immediately before, no
ſmell was perceived, and the common air incum-
bent on the mixture was quite colourleſs.
Had theſe ſingular phenomena been noticed by
any chemiſt before the diſcovery of nitrous air, I
cannot imagine what hypotheſis he would have
formed for the explanation of them. Whatever it
had been, it muſt have been very wide of the truth;
whereas
SeET. VII.
405
NITROUS AIR.
whereas the whole proceſs admits of the eaſieſt ex-
planation imaginable by the help of my obſervations
on the decompoſition of nitrous air by the nitrous
acid.
Nitrous air is actually formed the moment that
the ſolution begins, but it is inſtantly decoinpoſed
by the ſtrong ſpirit of nitre in contact with it. By
the addition of the phlogiſton contained in the ni-
trous air, the pale fpirit of nitre aſſumes an orange
colour, and it is then much leſs able to decompoſe
the nitrous air ; which, therefore, riſes in bubbles
through it, and is not decompoſed till it comes to
the region of the pale acid lying upon it. But
when the whole body of the acid is ſaturated with
phlogiſton, then, and not before, the bubbles of ni-
trous air paſs freely through it, and may be collected.
On this account, it is not eaſy to aſcertain the
exact quantity of nitrous air yielded by the ſolution
of mercury, and, for the ſame reaſon, of other me-
tals too, in ſtrong ſpirit of nitre ; becauſe allow-
ance muſt be made for the quantity that will be
imbibed by the acid itſelf, which muſt be ſaturated
before any can be collected; whereas, when the acid
is much diluted with water, it is not ſo capable of
decompoſing this air, and therefore, in general, it
may
be collected from the moment that the ſolution
begins.
It
4
+
406
OBSERVATIONS ON
Part II.
It is very remarkable, that when copper is dif-
ſolved in pale ſpirit of nitre, even diluted with much
water, though the ſolution is evidently the moſt ra-
pid at the firſt, the produce of air is very trifling for
a conſiderable time, and the quantity collected in-
creaſes very gradually; whereas when the orange co-
loured acid is employed, in the ſame diluted ſtate,
the nitrous air is collected immediately, and the
production is the moſt copious at the firſt.
When I diffolved a quantity of copper in ſtrong
ſpirit of nitre half diluted with water, no air what-
ever'was produced, though the metal was complete-
ly diſſolved.
When, in the folution of mercury, I uſed the
green ſpirit of nitre, inſtead of the pale coloured
and ſtrongeſt acid, the phenomena were not ma-
terially different from thoſe deſcribed above. The
lower part of the acid next to the mercury aſſumed
a deeper green, but it never became orange co-
loured.
SEC-
Seit. VIII.
407
NITROUS AIR.
11
SECTION
SECTION VIII. .
Miſcellaneous Properties of nitrous Air.
1. Of the freezing of Water impregnated with nitrous
Air,
IH
HAVE obſerved, that water diſcharges all the
fixed air it had imbibed the moment that it is
converted into ice. The fame is the caſe with wa-
ter impregnated with nitrous air, as appears by the
following experiment, made with a view both to this
circumſtance, and alſo to the earthy precipitate depo-
ſited by water thus impregnated.
Having impregnated a quantity of water with ni-
trous air, I expoſed it to the froſt, and obſerved that
it did not freeze quite ſo foon as a quantity of the
fame water which had not been ſo impregnated, ex-
poſed in the ſame manner. The ice of the impreg-
nated water was full of very ſmall bubbles, and
when it was thawed did not turn the juice of turnſole
red in the ſmalleſt degree. It alſo made a conſider-
I
able
408
Part II.
OBSERVATIONS ON
able precipitate of a very white matter, exactly like
that which I procured from the water impregnated
with nitrous air from biſmuth. This nitrous air,
however, had been procured from copper.
Having expoſed to the froſt a quantity of water
which had been a long time before impegnated
with nitrous air, and which had ſpontaneouſly de-
poſited a browniſh ſediment, it now depoſited more
of the ſame colour.
2. Of the burning of a Mixture of nitrous and in-
flammable Air.
Inflammable air with a mixture of nitrous air
burns with a green fame.
This makes a very
pleaſing experiment when it is properly conduct-
ed. As, for ſome time, I chiefly made uſe of
copper for the generation of nitrous air, I firſt aſcribed
this circumſtance to that property of this metal,
by which it burns with a green flame; but I was
preſently ſatisfied that it muſt ariſe from the ſpirit
of nitre, for the effect is the very fame from which
ever of the metals the nitrous air is extracted, all
of which I tried for this purpoſe, even ſilver and
gold. When a candle is extinguiſhed, as it never
fails to be, in nitrous air, the flame feems to be a
little
5
Sext. VIII.
409
NITROUS AIR.
little enlarged at its edges, by another bluiſh Aame
added to it juſt before its extinction.
3. Of Plants and Animals in nitrous Air.
Plants die very ſoon, both in nitrous air, and alſo
in common air faturated with nitrous air, but efpe-
cially in the former.
This kind of air is as noxious as any whatever, a
mouſe dying the moment it is put into it; but frogs and
ſnails (and therefore, probably, other animals whoſe re-
ſpiration is not frequent) will bear being expuled to
it a conſiderable time, though they die at length.
A frog put into nitrous air ſtruggled much for two
or three minutes, and moved now and then for a
quarter of an hour, after which it was taken out,
but did not recover.
There is ſomething remarkable in the effect of
nitrous air on inſeats that are put into it. Wafps
always died the moment they were put into the ni-
trous air. I could never obſerve that they made
the leaſt motion in it, nor could they be recovered
to life afterwards. This was alſo the caſe in general
with ſpiders, flies, and butterflies. Sometimes, how-
ever, ſpiders would recover after being expoſed
about a minute to this kind of air.
Еe
4. Of
410
Part II.
O.BSERVATIONS ON
4. Of the Uſe of nitrous Air in Clyſters.
Conſidering how fatal ritrous air is to inſects,
and likewiſe its great antiſeptic power, I conceived
that conſiderable uſe might be made of it in me-
dicine, eſpecially in the form of clyſters, in which
fixed air had been applied with ſome ſucceſs; and
in order to try whether the bowels of an animal
would bear the injection of it, I contrived, with
the help of Mr. Hey, to convey a quantity of it
up the anus of a dog. But he gave manifeſt ſigns
of uneaſineſs as long as he retained it, which was
a conſiderable time, though in a few hours after-
wards he was as lively as ever, and ſeemed to have
ſuffered nothing from the operation.
Perhaps if nitrous air was diluted either with
common air, or fixed air, the bowels might bear
it better, and ſtill it might be deſtructive to worinis
of all kinds, and be of uſe to check, or correct, pu-
trefaction in the inteſtinal canal, or other
parts
of
the ſyſtem. I repeat it once more, that, being no
phyſician, I run no riſk by ſuch propoſals as theſe ;
and I cannot help flattering myſelf that, in time,
very great medicinal uſe will be made of the ap-
plication of theſe different kinds of air to the animal
ſyſtem,
+
SeEZ. VIII. NITROUS AIR. 411
ſyſtem. Let ingenious phyſicians attend to this
ſubject, and endeavour to lay hold of the new han-
dle which is now prefented them, before it be ſeized
by raſh emperics; who, by an indiſcriminate and
injudicious application, often ruin the credit of
things and proceſſes, which might otherwiſe make
an uſeful addition to the materia and ars medica.
END OF THE FIRST VOLUME,
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