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Carbonic oxide . " . . . 40

Coal-gas . ; V-; J . . . 32

The difference in the facility of leakage was one reason of
the difference in the pressure applied. I found it impossible,
from this cause, to raise the pressure of hydrogen higher than
twenty-seven atmospheres by an apparatus that was quite tight
enough to confine nitrogen up to double that pressure.

M. Cagniard de la Tour has shown that at a certain tempe-
rature, a liquid, under sufficient pressure, becomes clear trans-
parent vapour or gas, having the same bulk as the liquid. At
this temperature, or one a little higher, it is not likely that
any increase of pressure, except perhaps one exceedingly great,
would convert the gas into a liquid. Now the temperature of
166 below 0, low as it is, is probably above this point of
temperature for hydrogen, and perhaps for nitrogen and oxy-
gen, and then no compression without the conjoint application
of a degree of cold below that we have as yet obtained, can be
expected to take from them their gaseous state. Further, as
ether assumes this state before the pressure of its vapour has
acquired thirty-eight atmospheres, it is more than probable
that gases which can resist the pressure of from twenty-seven
to fifty atmospheres at a temperature of 166 below could
never appear as liquids, or be made to lose their gaseous state
at common temperatures. They may probably be brought into
the state of very condensed gases, but not liquefied.

Some very interesting experiments on the compression of
gases have been made by M. G. Aime*, in which oxygen,

* Annales de Chimie, 1843, viii. 275.



1844.] of Bodies generally existing as Gases. 117

olefiant, nitric oxide, carbonic oxide, fluosilicon, hydrogen,
and nitrogen gases were submitted to pressures, rising up to
220 atmospheres in the case of the last two ; but this was in
the depths of the sea where the results under pressure could
not be examined. Several of them were diminished in bulk in
a ratio far greater than the pressure put upon them ; but both
M. Cagniard de la Tour and M. Thilorier have shown that
this is often the case whilst the substance retains the gaseous
form. It is possible that olefiant gas and fluosilicon may have
liquefied down below, but they have not yet been seen in the
liquid state except in my own experiments, and in them not at
temperatures above 40 Fahr. The results with oxygen are so
unsteady and contradictory as to cause doubt in regard to those
obtained with the other gases by the same process.

Thus, though as yet I have not condensed oxygen, hydrogen,
or nitrogen, the original objects of my pursuit, I have added six
substances, usually gaseous, to the list of those that could pre-
viously be shown in the liquid state, and have reduced seven,
including ammonia, nitrous oxide, and sulphuretted hydrogen,
into the solid form. And though the numbers expressing ten-
sion of vapour cannot (because of the difficulties respecting the
use of thermometers and the apparatus generally) be con-
sidered as exact, I am in hopes they will assist in developing
some general law governing the vaporization of all bodies, and
also in illustrating the physical state of gaseous bodies as they
are presented to us under ordinary temperature and pressure.

Royal Institution, Nov. 15, 1844.



NOTE. ADDITIONAL REMARKS RESPECTING THE CONDENSATION OF

GASES.
[Received February 20, Read February 20, 1845.]

Nitrous Oxide. Suspecting the presence on former occa-
sions of nitrogen in the nitrous oxide, and mainly because of
muriate in the nitrate of ammonia used, I prepared that salt in
a pure state from nitric acid and carbonate of ammonia pre-
viously proved, by nitrate of silver, to be free from muriatic
acid. After the nitrous oxide prepared from this salt had re-
mained for some days in well-closed bottles in contact with a



us



On the Liquefaction and Solidification [1844,



little water, I condensed it in the manner already described,
and when condensed I allowed half the fluid to escape in vapour,
that as much as possible of the less condensable portion might
be carried off. In this way as much gas as would fill the capa-
city of the vessels twenty or thirty times or more was allowed
to escape. Afterwards the following series of pressures was
obtained :



Fahr.


Atmospheres.


Fahr.


Atmospheres.


Fahr.


Atmospheres.


O




o




o




-125


:* *.' I'OO


-70


. . 4-11


-15


. . 14-69


-120


a* MO


-65


4-70


-10


. . 16-15


-115


wh 1-22


-60


. . 5-36


5


. . 17-70


-110


*v 1-37


-55


. . 6-09





. . 19-34


-105


* J 1-55


-50


. . 6-89


5


-r.?v 21-07


-100


. .. 1-77


-45


. . 7-76


10


. . 22-89


- 95


;,i: 2-03


-40


V*. 8-71


15


. . 24-80


- 90


:/* *v 2-34


-35


. . 9-74


20


. . 26-80


- 85


^4^ 2-70


-30


. . 10-85


25


. . 28-90


- 80


.* .' 8-11


-25


. . 12-04


30


. . 31-10


- 75


. . 3-58


-20


. . 13-32


35


. . 33-40



These numbers may all be taken as the results of experi-
ments. Where the temperatures are not those actually ob-
served, they are in almost all cases within a degree of it, and
proportionate to the effects really observed. The departure
of the real observations from the numbers given is very small.
This Table I consider as far more worthy of confidence than
the former, and yet it is manifest that the curve is not consist-
ent with the idea of a pure single substance, for the pressures
at the lowest temperature are too high. I believe that there
are still two bodies present, and that the more volatile, as
before said, is condensable in the liquid of the less volatile ; but
I think there is a far smaller proportion of the more volatile
(nitrogen, or whatever it may be) than in the former case.

Olefiant Gas. The olefiant gas condensed in the former
experiment was prepared in the ordinary way, using excellent
alcohol and sulphuric acid ; then washed by agitation with
about half its bulk of water, and finally left for three days over
a thick mixture of lime and water with occasional agitation.
In this way all the sulphurous and carbonic acids were removed,
and I believe all the ether, except such minute portions as



1844.] of Bodies ge tier all// existing as Gases. 119

could not interfere with my results. In respect of the ether, I
have since found that the process is satisfactory ; for when I
purposely added ether vapour to air, so as to increase its bulk
by one-third, treatment like that above removed it, so as to
leave the air of its original volume. There was yet a slight
odour of ether left, but not so much as that conferred by adding
one volume of the vapour of ether to 1200 or 1500 volumes of
air. I find that when air is expanded ^th or ^rd more by the
addition of the vapour of ether, washing first of all with about
^th of its volume of water, then again with about as much
water, and lastly with its volume of water, removes the ether to
such a degree, that though a little smell may remain, the air is
of its original volume.

As already stated, it is the presence of other and more vola-
tile hydrocarbons than olefiant gas, which the tensions obtained
seemed to indicate, both in the gas and the liquid resulting
from its condensation. In a further search after these I dis-
covered a property of olefiant gas which I am not aware is
known (since I do not find it referred to in books), namely its
ready solubility in strong alcohol, ether, oil of turpentine, and
such like bodies*. Alcohol will take up two volumes of this
gas ; ether can absorb two volumes ; oil of turpentine two
volumes and a half; and olive oil one volume by agitation at
common temperatures and pressure ; consequently, when a
vessel of olefiant gas is transferred to a bath of any of these
liquids and agitated, absorption quickly takes place.

Examined in this way, I have found no specimen of olefiant
gas that is entirely absorbed ; a residue always remains, which,
though I have not yet had time to examine it accurately, ap-
pears to be light carburetted hydrogen ; and I have no doubt
that this is the substance which has mainly interfered in my
former results. This substance appears to be produced in
every stage of the preparation of olefiant gas. On taking six
different portions of gas at different equal intervals, from first
to last, during one process of preparation, after removing the
sulphurous and carbonic acid and the ether as before described,
then the following was the proportion per cent, of insoluble

* Water, as Berzelius and others have pointed out, dissolves about |th its
volume of olefiant gas, but I find that it also leaves an insoluble residue, which
burns like light carburetted hydrogen.



120



On the Liquefaction and Solidification [1844.



gas in the remainder when agitated with oil of turpentine: 10*5 ;
10; 10-1; 13-1; 28'3; 6l'S. Whether carbonic oxide was
present in any of these undissolved portions I cannot at pre-
sent say.

In reference to the part dissolved, I wish as yet to guard
myself from being supposed to assume that it is one uniform
substance ; there is indeed little doubt that the contrary is
true ; for whilst a volume of oil of turpentine introduced into
twenty times its volume of olefiant gas cleared from ether and
the acids, absorbs 2J volumes of the gas, the same volume of
fresh oil of turpentine brought into similar contact with abun-
dance of the gas which remains when one-half has been removed
by solution only dissolved 1*54 part, yet there was an abundant
surplus of gas which would dissolve in fresh oil of turpentine
at this latter rate. When two-thirds of a portion of fresh ole-
fiant gas were removed by solution, the most soluble portion of
that which remained required its bulk of fresh oil of turpentine
to dissolve it. Hence at first one volume of camphine dis-
solved 2*50, but when the richer portion of the gas was re-
moved, one volume dissolved 1*54 part; and when still more of
the gas was taken away by solution, one volume of camphine
dissolved only one volume of the gas. This can only be ac-
counted for by the presence of various compounds in the solu-
ble portion of the gas.

A portion of good olefiant gas was prepared, well agitated
with its bulk of water in close vessels, left over lime and water
for three days, and then condensed as before. When much
liquid was condensed, a considerable proportion was allowed to
escape to sweep out the uncondensed atmosphere and the more
condensable vapours ; and then the following pressures were



tnospheres.

4-60


Fahr.
o

-65


Atmospheres.

. . 8-30


Fahr.
o

-30


Atmospheres.

. . 16-22


4-82


-60


9-14


-25


'; . 17-75


5-10


-55


. . 10-07


-20


. . 19-38


5-44


-50


. . 11-10


-15


. . 21-11


5-84


-45


... 12-23


-10


. . 22-94


6-32


-40


. . 13-46


- 5


. . 24-87


6-89


-35


. . 14-79





:'.'. 26-90


7-55











1844.] of Bodies generally existing as Gases* 121

On examining the form of the curve given by these press-
ures, it is very evident that, as on former occasions, the press-
ures at low temperatures are too great to allow the condensed
liquid to be considered as one uniform body, and the form of
the curve at the higher pressures is quite enough to prove that
no ether was present either in this or the former fluids. On
permitting the liquid in the tube to expand into gas, and treat-
ing 100 parts of that gas with oil of turpentine, eighty-nine
parts were dissolved, and eleven parts remained insoluble.
There can be no doubt that the presence of this latter sub-
stance, soluble as it is under pressure in the more condensable
portions, is the cause of the irregularity of the curve, and the
too high pressure at the lower temperatures.

The ethereal solution of olefiant gas being mixed with eight
or nine times its volume of water, dissolved, and gradually
minute bubbles of gas appeared, the separation of which was
hastened by a little heat. In this way about half the gas dis-
solved was re-obtained, and burnt like very rich olefiant gas.
One volume of the alcoholic solution, with two volumes of
water, gave very little appearance of separating gas. Even the
application of heat did not at first cause the separation, but gra-
dually about half the dissolved olefiant gas was liberated.

The separation of the dissolved gas by water, heat, or change
of pressure from its solutions, will evidently supply means of
procuring olefiant gas in a greater state of purity than hereto-
fore ; the power of forming these solutions will also very much
assist in the correct analysis of mixtures of hydrocarbons. I
find that light carburetted hydrogen is hardly sensibly soluble
in alcohol or ether, and in oil of turpentine the proportion dis-
solved is not probably T yth the volume of the fluid employed ;
but the further development of these points I must leave for
the present.

Carbonic Acid. This liquid may be retained in glass tubes
furnished with cemented caps, and closed by plugs or stop-
cocks, as described ; but it is important to remember the soft-
ening action on the cement, which, being continued, at last re-
duces its strength below the necessary point. A tube of this
kind was arranged on the 10th of January and left; on the 15th
of February it exploded, not by any fracture of the tube, for
that remained unbroken, but simply by throwing off the cap



On the Liquefaction and Solidification [1 844,

through a failure of the cement. Hence the cement joints
should not be used for long experiments, but only for those
enduring for a few days.

Oxygen. Chlorate of potassa was melted and pulverized.
Oxide of manganese was pulverized, heated red-hot for half an
hour, mixed whilst hot with the chlorate, and the mixture put
into a long strong glass generating tube with a cap cemented
on, and this tube then attached to another with a gauge for
condensation. The heat of a spirit-lamp carefully applied pro-
duced the evolution of oxygen without any appearance of water,
and the tubes, both hot and cold, sustained the force generated.
In this manner the pressure of oxygen within the apparatus
was raised as high as 58*5 atmospheres, whilst the temperature
at the condensing place was reduced as low as 140 Fahr.,
but no condensation appeared. A little above this pressure
the cement of two of the caps began to leak, and I could carry
the observation no further with this apparatus.



From the former scanty and imperfect expressions of the
elasticity of the vapour of the condensed gases, Dove was led
to put forth a suggestion*, whether it might not ultimately
appear that the same addition of heat (expressed in degrees of
the thermometer) caused the same additional increase of ex-
pansive force for all gases or vapours in contact with their
liquids, provided the observation began with the same pressure
in all. Thus to obtain the difference between forty-four and
fifty atmospheres of pressure, either with steam or nitrous
oxide, nearly the same number of degrees of heat were re-
quired ; to obtain the difference between twenty and twenty-
five atmospheres, either with steam or muriatic acid, the same
number were required. Such a law would of course make the
rate of increasing expansive force the same for all bodies, and
the curve laid down for steam would apply to every other
vapour. This, however, does not appear to be the case. That
the force of the vapour increases in a geometrical ratio for
equal increments of heat is true for all bodies, but the ratio is
not the same for all. As far as observations upon the follow-

* Poggendorff 's Annalen, xxiii. 290 ; or Thomson on Heat and Electri-
city, p. 9.



1844.] of Bodies generally existing as Gases.

ing substances, namely, water, sulphurous acid, cyanogen, am-
monia, arseniuretted hydrogen, sulphuretted hydrogen, muri-
atic acid, carbonic acid, olefiant gas, &c., justify any conclusion
respecting a general law, it would appear that the more volatile
a body is, the more rapidly does the force of its vapour in-
crease by further addition of heat, commencing at a given point
of pressure for all ; thus for an increase of pressure from two
to six atmospheres, the following number of degrees require to
be added for the different bodies named : water 69, sulphurous
acid 63, cyanogen 64*5, ammonia 60, arseniuretted hydro-
gen 54, sulphuretted hydrogen 56*5, muriatic acid 43,
carbonic acid 32'5 t nitrous oxide 30; and though some of
these numbers are not in the exact order, and in other cases,
as of olefiant gas and nitrous oxide, the curves sometimes even
cross each other, these circumstances are easily accounted for
by the facts already stated of irregular composition and the
inevitable errors of first results. There seems every reason
therefore to expect that the increasing elasticity is directly as
the volatility of the substance, and that by further and more
correct observation of the forces, a general law may be deduced,
by the aid of which, and only a single observation of the force
of any vapour in contact with its fluid, its elasticity at any other
temperature may be obtained.

Whether the same law may be expected to continue when
the bodies approach near to the Cagniard de la Tour state is
doubtful. That state comes on sooner in reference to the press-
ure required, according as the liquid is lighter and more expan-
sible by heat and its vapour heavier, hence indeed the great
reason for its facile assumption by ether. But though with
ether, alcohol and water, that substance which is most volatile
takes up this state with the lowest pressure, it does not follow
that it should always be so ; and in fact we know that ether
takes up this state at a pressure between thirty-seven and thirty-
eight atmospheres, whereas muriatic acid, nitrous oxide, car-
bonic acid and olefiant gas, which are far more volatile, sustain
a higher pressure than this without assuming that peculiar state,
and whilst their vapours and liquids are still considerably dif-
ferent from each other. Now whether the curve which ex-
presses the elastic force of the vapour of a given fluid for in-
creasing temperatures continues undisturbed after that fluid



124 On the Liquefaction of Gases. [1824.

has passed the Cagniard de la Tour point or not is not known,
and therefore it cannot well be anticipated whether the coming
on of that state sooner or later with particular bodies will in-
fluence them in relation to the more general law referred to
above.

The law already suggested gives great encouragement to the
continuance of those efforts which are directed to the conden-
sation of oxygen, hydrogen and nitrogen, by the attainment
and application of lower temperatures than those yet applied.
If to reduce carbonic acid from the pressure of two atmospheres
to that of one, we require to abstract only about half the num-
ber of degrees that is necessary to produce the same effect with
sulphurous acid, it is to be expected that a far less abstraction
will suffice to produce the same effect with nitrogen or hydro-
gen, so that further diminution of temperature and improved
apparatus for pressure may very well be expected to give us
these bodies in the liquid or solid state.

Royallnstitution, Feb. 19, 1845.



Historical Statement respecting the Liquefaction of Gases *.

I WAS not aware at the time when I first observed the liquefac-
tion of chlorine gas f , nor until very lately, that any of the
class of bodies called gases, had been reduced into the fluid
form; but having during the last few weeks sought for in-
stances where such results might have been afforded without
the knowledge of the experimenter, I was surprised to find
several recorded cases. I have thought it right therefore to
bring these cases together, and only justice to endeavour to
secure for them a more general attention than they appear as
yet to have gained. I shall notice in chronological order, the
fruitless, as well as the successful attempts, and those which
probably occurred without being observed, as well as those
which were remarked and described as such.

Carbonic Acid, $c. The ( Philosophical Transactions ' for
1797 contain, p. 222, an account of experiments made by
Count Rumford, to determine the force of fired gunpowder.

* Quarterly Journal of Science, xvi. 229.

f Philosophical Transactions, 1823, pp. 160, 189 or page 85.



1824.] On the Liquefaction of Gases. 125

Dissatisfied both with the deductions drawn, and the means
used previously, that philosopher proceeded to fire gunpowder
in cylinders of a known diameter and capacity, and closed by a
valve loaded with a weight that could be varied at pleasure. By
making the vessel strong enough and the weight sufficiently
heavy, he succeeded in confining the products within the space
previously occupied by the powder. The Count's object in-
duced him to vary the quantity of gunpowder in different
experiments, and to estimate the force exerted only at the
moment of ignition, when it was at its maximum. This force,
which he found to be prodigious, he attributes to aqueous
vapour intensely heated, and makes no reference to the force of
the gaseous bodies evolved. Without considering the phe-
nomena which it is the Count's object to investigate, it may be
remarked, that in many of the experiments made by him, some
of the gases, and especially carbonic acid gas, were probably
reduced to the liquid state. The Count says,

" When the force of the generated elastic vapour was suffi-
cient to raise the weight, the explosion was attended by a very
sharp and surprisingly loud report ; but when the weight was
not raised, as also when it was only a little moved, but not suffi-
ciently to permit the leather stopper to be driven quite out of
the bore, and the elastic fluid to make its escape, the report was
scarcely audible at a distance of a few paces, and did not at all
resemble the report which commonly attends the explosion of
gunpowder. It was more like the noise which attends the
breaking of a small glass tube, than anything else to which
it could be compared. In many of the experiments, in which
the elastic vapour was confined, this feeble report attending the
explosion of the powder was immediately followed by another
noise totally different from it, which appeared to be occasioned
by the falling back of the weight upon the end of the barrel,
after it had been a little raised, but not sufficiently to permit the
leather stopper to be driven quite out of the bore. In some of
these experiments a very small part only of the generated elastic
fluid made its escape ; in these cases the report was of a pe-
culiar kind, and though perfectly audible at some considerable
distance, yet not at all resembling the report of a musket. It
was rather a very strong sudden hissing, than a clear, distinct
and sharp report. " <* ;.<



126 On the Liquefaction of Gases. [1S24.

In another place it is said, " What was very remarkable in
all these experiments, in which the generated elastic vapour
was completely confined, was the small degree of expansive
force which this vapour appeared to possess, after it had been
suffered to remain a few minutes, or even only a few seconds,
confined in the barrel ; for upon raising the weight by means
of its lever, and suffering this vapour to escape, instead of
escaping with a loud report it rushed out with a hissing noise,
hardly so loud or so sharp as the report of a common air-gun,
and its effects against the leather stopper, by which it assisted
in raising the weight, were so very feeble as not to be sensible."
This the Count attributes to the formation of a hard mass, like
a stone, within the cylinder, occasioned by the condensation of
what was, at the moment of ignition, an elastic fluid. Such a
substance was always found in these cases ; but when the ex-
plosion raised the weight and blew out the stopper, nothing
of this kind remained.

The effects here described, both of elastic force and its cessa-
tion on cooling, may evidently be referred as much to carbonic
acid and perhaps other gases as to water. The strong sudden
hissing observed as occurring when only a little of the products
escaped, may have been due to the passage of the gases into the
air, with comparatively but little water, the circumstances being
such as were not sufficient to confine the former, though they
might the latter ; for it cannot be doubted but that in similar
circumstances the elastic force of carbonic acid would far sur-
pass that of water. Count Rumford says, that the gunpowder



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