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of chloride of silver were obtained from the solution, and if
this be considered as equivalent to 18 grs. of chlorine, then
the 65 grs. of hydrate must have contained 47 grs. of water,
or per cent.

Chlorine . , * . 27-7

Water . . > * 72'3

This nearly accords with 10 proportionals of water to 1 of
chlorine, and I have chosen it because it gave the largest pro-
portion of chlorine of any experiment I made. It is evident
that any loss or error either in the drying the crystals, or in
the conversion of the chlorine into muriatic acid by the am-
monia, would tend to diminish the proportion of that element ;
and it is even possible that the above proportion of chlorine is
under-rated, but I .believe it to be near the truth. The mean
of several other experiments gave

Chlorine .... 26*3

Water .... 73'6

Note. Since writing the above, Mr. Faraday has succeeded in condensing
chlorine into a liquid ; for this purpose a portion of the solid and dried hy-
drate of chlorine is put into a small bent tube and hermetically sealed ; it is
then heated to about 100, and a yellow vapour is formed which condenses
into a deep yellow liquid heavier than water (sp. gr. probably about 1'3).
Upon relieving the pressure by breaking the tube, the condensed chlorine
instantly assumes its usual state of gas or vapour.

When perfectly dry chlorine is condensed into a tube by means of a
syringe, a portion of it assumes the liquid form under a pressure equal to
that of 4 or 5 atmospheres.

By putting some muriate of ammonia and sulphuric acid into the opposite
ends of a bent glass tube, sealing it hermetically, and then suffering the acid
to run upon the salt, muriatic acid is generated under such pressure as causes
it to assume the liquid form ; it is of an orange colour, lighter than sulphu-
ric acid, and instantly assumes the gaseous state when the pressure is removed.
Sir H. Davy has given an account of this experiment to the Royal Society.
It is probable that by a similar mode of treatment several other gases may
be liquefied.



1823.] On Fluid Chlorine. 85

On Fluid Chlorine*.
[Read March 13, 1823.]

IT is well known that before the year 1810 the solid substance
obtained by exposing chlorine, as usually procured, to a low
temperature, was considered as the gas itself reduced into that
form ; and that Sir Humphry Davy first showed it to be a
hydrate, the pure dry gas not being condensible even at a tem-
perature of 40 F.

I took advantage of the late cold weather to procure cry-
stals of this substance for the purpose of analysis. The
results are contained in a short paper in the Quarterly Journal
of Science, vol. xv.f Its composition is very nearly 27*7 chlo-
rine, 72'3 water, or 1 proportional of chlorine and 10 of water.

The President of the Royal Society having honoured me
by looking at these conclusions, suggested, that an exposure
of the substance to heat under pressure would probably lead
to interesting results ; the following experiments were com-
menced at his request. Some hydrate of chlorine was pre-
pared, and, being dried as well as could be by pressure in
bibulous paper, was introduced into a sealed glass tube, the
upper end of which was then hermetically closed. Being
placed in water at 60, it underwent no change ; but when put
into water at 100, the substance fused, the tube became filled
with a bright yellow atmosphere, and on examination was
found to contain two fluid substances : the one, about three-
fourths of the whole, was of a faint yellow colour, having very
much the appearance of water ; the remaining fourth was a
heavy bright yellow fluid, lying at the bottom of the former,
without any apparent tendency to mix with it. As the tube
cooled, the yellow atmosphere condensed into more of the
yellow fluid, which floated in a film on the pale fluid, looking
very like chloride of nitrogen ; and at 70 the pale portion
congealed, although even at 3 the yellow portion did not
solidify. Heated up to 100 the yellow fluid appeared to boil,
and again produced the bright coloured atmosphere.

By putting the hydrate into a bent tube, afterwards herme-
tically sealed, I found it easy, after decomposing it by a heat
of 100, to distil the yellow fluid to one end of the tube, and to

* Phil. Trans. 1823, p. 160; also Phil. Mag. Ixii. p. 413. t See page 81.



80 On Fluid Chlorine. [1823.

separate it from the remaining portion. In this way a more
complete decomposition of the hydrate was effected ; and, when
the whole was allowed to cool, neither of the fluids solidified at
temperatures above 34, and the yellow portion not even at 0.
When the two were mixed together, they gradually combined
at temperatures below 60, and formed the same solid sub-
stances as that first introduced. If, when the fluids were sepa-
rated, the tube was cut in the middle, the parts flew asunder
as if with an explosion, the whole of the yellow portion dis-
appeared, and there was a powerful atmosphere of chlorine
produced ; the pale portion on the contrary remained, and when
examined, proved to be a weak solution of chlorine in water,
with a little muriatic acid, probably from the impurity of the
hydrate used. When that end of the tube in which the yellow
fluid lay was broken under a jar of water, there was an imme-
diate production of chlorine gas.

I at first thought that muriatic acid and euchlorine had been
formed ; then, that two new hydrates of chlorine had been pro-
duced ; but at last I suspected that the chlorine had been
entirely separated from the water by the heat, and condensed
into a dry fluid by the mere pressure of its own abundant
vapour. Jf that were true, it followed that chlorine gas, when
compressed, should be condensed into the same fluid ; and as
the atmosphere in the tube in which the fluid lay was not very
yellow at 50 or 60, it seemed probable that the pressure
required was not beyond what could readily be obtained by a
condensing syringe. A long tube was therefore furnished with
a cap and stopcock, then exhausted of air and filled with chlo-
rine, and being held vertically with the syringe upwards, air was
forced in, which thrust the chlorine to the bottom of the tube,
and gave a pressure of about 4 atmospheres. Being now
cooled, there was an immediate deposit in films, which appeared
to be hydrate, formed by water contained in the gas and
vessels, but some of the yellow fluid was also produced. As
this, however, might also contain a portion of the water present,
a perfectly dry tube and apparatus were taken, and the chlo-
rine left for some time over a bath of sulphuric acid before
it was introduced. Upon throwing in air and giving pressure,
there .was now no solid film formed, but the clear yellow fluid
was deposited, and more abundantly still upon cooling. After



1823.] On Fluid Chlorine. 87

remaining some time it disappeared, having gradually mixed
with the atmosphere above it ; but every repetition of the ex-
periment produced the same results.

Presuming that I had now a right to consider the yellow
fluid as pure chlorine in the liquid state, I proceeded to ex-
amine its properties, as well as I could when obtained by heat
from the hydrate. However obtained, it always appears very
limpid and fluid, and excessively volatile at common pressure.
A portion was cooled in its tube to 0; it remained fluid.
The tube was then opened, when a part immediately flew off,
leaving the rest so cooled, by the evaporation, as to remain a
fluid under the atmospheric pressure. The temperature could
not have been higher than 40 in this case ; as Sir Humphry
Davy has shown that dry chlorine does not condense at that
temperature under common pressure. Another tube was
opened at a temperature of 50 ; a part of the chlorine vola-
tilized, and cooled the tube so much as to condense the atmo-
spheric vapour on it into ice.

A tube having the water at one end and the chlorine at the
other was weighed, and then cut in two ; the chlorine imme-
diately flew off, and the loss being ascertained was found to be
1-6 grain : the water left was examined and found to contain
some chlorine : its weight was ascertained to be 5*4 grains.
These proportions, however, must not be considered as indi-
cative of the true composition of hydrate of chlorine ; for, from
the mildness of the weather during the time when these expe-
riments were made, it was impossible to collect the crystals
of hydrate, press and transfer them, without losing much
chlorine ; and it is also impossible to separate the chlorine and
water in the tube perfectly, or keep them separate, as the
atmosphere within will combine with the water, and gradually
re-form the hydrate.

Before cutting the tube, another tube had been prepared
exactly like it in form and size, and a portion of water intro-
duced into it, as near as the eye could judge, of the same bulk
as the fluid chlorine ; this water was found to weigh 1*2 grain;
a result, which, if it may be trusted, would give the specific
gravity of fluid chlorine as 1'33; and from its appearance in
and on water, this cannot be far wrong.



88 On the Condensation [1823,

NOTE ON THE CONDENSATION OF MURIATIC ACID GAS INTO THE LIQUID
FORM. BY SIR H. DAVY, Bart., Pres. R.S.

In desiring Mr. Faraday to expose the hydrate of chlorine
to heat in a closed glass tube, it occurred to me that one of
three things would happen : that it would become fluid as a
hydrate ; or that a decomposition of water would occur, and
euchlorine and muriatic acid be formed ; or that the chlorine
would separate in a condensed state. This last result having
been obtained, it evidently led to other researches of the same
kind. I shall hope, on a future occasion, to detail some ge-
neral views on the subject of these researches. I shall now
merely mention, that by sealing muriate of ammonia and sul-
phuric acid in a strong glass tube, and causing them to act
upon each other, I have procured liquid muriatic acid : and by
substituting carbonate for muriate of ammonia, I have no doubt
that carbonic acid may be obtained, though in the only trial I
have made the tube burst. I have requested Mr. Faraday to
pursue these experiments, and to extend them to all the gases
which are of considerable density, or to any extent soluble in
water ; and I hope soon to be able to lay an account of his
results, with some applications of them that I propose to make,
before the Society.

I cannot conclude this note without observing, that the ge-
neration of elastic substances in close vessels, either with or
without heat, offers much more powerful means of approxi-
mating their molecules than those dependent upon the appli-
cation of cold, whether natural or artificial; for as gases di-
minish only about ^j in volume for every degree of Fahr-
enheit's scale, beginning at ordinary temperatures, a very
slight condensation only can be produced by the most power-
ful freezing mixtures not half as much as would result from
the application of a strong flame to one part of a glass tube,
the other part being of ordinary temperature : and when at-
tempts are made to condense gases into fluids by sudden me-
chanical compression, the heat, instantly generated, presents a
formidable obstacle to the success of the experiment ; whereas
in the compression resulting from their slow generation in
close vessels, if the process be conducted with common precau-
tions, there is no source of difficulty or danger ; and it may be



1823.] of several Gases into Liquids. 89

easily assisted by artificial cold in cases when gases approach
near to that point of compression and temperature at which
they become vapours.

On the Condensation of several Gases into Liquids *.
[Read April 10, 1823.]

I HAD the honour, a few weeks since, of submitting to the
Royal Society a paper on the reduction of chlorine to the
liquid state. An important note was added to the paper by
the President, on the general application of the means used in
this case to the reduction of other gaseous bodies to the liquid
state ; and in illustration of the process, the production of
liquid muriatic acid was described. Sir Humphry Davy did
me the honour to request I would continue the experiments,
which I have done under his general direction, and the follow-
ing are some of the results already obtained :

Sulphurous Acid. Mercury and concentrated sulphuric acid
were sealed up in a bent tube, and, being brought to one end,
heat was carefully applied, whilst the other end was preserved
cool by wet bibulous paper. Sulphurous acid gas was pro-
duced where the heat acted, and was condensed by the sul-
phuric acid above ; but when the latter had become saturated,
the sulphurous acid passed to the cold end of the tube, and
was condensed into a liquid. When the whole tube was cold,
if the sulphurous acid were returned on to the mixture of sul-
phuric acid and sulphate of mercury, a portion was reabsorbed,
but the rest remained on it without mixing.

Liquid sulphurous acid is very limpid and colourless, and
highly fluid. Its refractive power, obtained by comparing it in
water and other media with water contained in a similar tube,
appeared to be nearly equal to that of water. It does not soli-
dify or become adhesive at a temperature of F. When a
tube containing it was opened, the contents did not rush out as
with explosion, but a portion of the liquid evaporated rapidly,
cooling another portion so much as to leave it in the fluid state
at common barometric pressure. It was however rapidly dis-
sipated, not producing visible fumes, but producing the odour
of pure sulphurous acid^ and leaving the tube quite dry. A

* Philosophical Transactions, 1823, p. 189; also Phil. Mag. Ixii. p. 416.



90 On the Condensation [1823,

portion of the vapour of the fluid received over a mercurial
bath, and examined, proved to be sulphurous acid gas. A
piece of ice dropped into the fluid instantly made it boil, from
the heat communicated by it.

To prove in an unexceptional manner that the fluid was pure
sulphurous acid, some sulphurous acid gas was carefully pre-
pared over mercury, and a long tube perfectly dry, and closed
at one end, being exhausted, was filled with it ; more sulphu-
rous acid was then thrown in by a condensing syringe, till there
were three or four atmospheres ; the tube remained perfectly
clear and dry ; but on cooling one end to 0, the fluid sulphu-
rous acid condensed, and in all its characters was like that pre-
pared by the former process.

A small gauge was attached to a tube in which sulphurous
acid was afterwards formed, and at a temperature of 45 F. the
pressure within the tube was equal to three atmospheres, there
being a portion of liquid sulphurous acid present : but as the
common air had not been excluded when the tube was sealed,
nearly one atmosphere must be due to its presence ; so that
sulphurous acid vapour exerts a pressure of about two atmo-
spheres at 45 F. Its specific gravity was nearly 1*42*.

Sulphuretted Hydrogen. A tube being bent, and sealed at
the shorter end, strong muriatic acid was poured in through a
small funnel, so as nearly to fill the short leg without soiling
the long one. A piece of platinum foil was then crumpled up

" * I am indebted to Mr. Davies Gilbert, who examined with much attention
the results of these experiments, for the suggestion of the means adopted to
obtain the specific gravity of some of these fluids. A number of small glass
bulbs were blown and hermetically sealed ; they were then thrown into alco-
hol, water, sulphuric acid, or mixtures of these, and when any one was found
of the same specific gravity as the fluid in which it was immersed, the specific
gravity of the fluid was taken : thus a number of hydrometrical bulbs were
obtained ; these were introduced into the tubes in which the substances were
to be liberated ; and ultimately, the dry liquids obtained, in contact with them.
It was then observed whether they floated or not, and a second set of experi-
ments were made with bulbs lighter or heavier as required, until a near ap-
proximation was obtained. Many of the tubes burst in the experiments, and
in others difficulties occurred from the accidental fouling of the bulb by the
contents of the tube. One source of error may be mentioned in addition to
those which are obvious, namely, the alteration of the bulk of the bulb by its
submission to the pressure required to keep the substance in the fluid state.



1823.] of several Gases into Liquids. 91

and pushed in, and upon that were put fragments of sulphuret
of iron, until the tube was nearly full. In this way action was
prevented until the tube was sealed. If it once commences, it
is almost impossible to close the tube in a manner sufficiently
strong, because of the pressing out of the gas. When closed,
the muriatic acid was made to run on to the sulphuret of iron,
and then left for a day or two. At the end of that time, much
protomuriate of iron had formed, and on placing the clean end
of the tube in a mixture of ice and salt, warming the other end
if necessary by a little water, sulphuretted hydrogen in the
liquid state distilled over.

The liquid sulphuretted hydrogen was colourless, limpid,
and excessively fluid. Ether, when compared with it in similar
tubes, appeared tenacious and oily. It did not mix with the
rest of the fluid in the tube, which was no doubt saturated,
but remained standing on it. When a tube containing it was
opened, the liquid immediately rushed into vapour ; and this
being done under water, and the vapour collected and exa-
mined, it proved to be sulphuretted hydrogen gas. As the
temperature of a tube containing some of it rose from to 45,
part of the fluid rose in vapour, and its bulk diminished ; but
there was no other change : it did not seem more adhesive at
than at 45. Its refractive power appeared to be rather
greater than that of water ; it decidedly surpassed that of sul-
phurous acid. A small gauge being introduced into a tube in
which liquid sulphuretted hydrogen was afterwards produced,
it was found that the pressure of its vapour was nearly equal
to 17 atmospheres at the temperature of 50.

The gauges used were made by drawing out some tubes at
the blowpipe table until they were capillary, and of a trumpet
form ; they were graduated by bringing a small portion of
mercury successively into their different parts ; they were then
sealed at the fine end, and a portion of mercury placed in the
broad end ; and in this state they were placed in the tubes, so
that none of the substances used or produced could get to
the mercury, or pass by it to the inside of the gauge. In esti-
mating the number of atmospheres, one has always been sub-
tracted for the air left in the tube.

The specific gravity of sulphuretted hydrogen appeared to
be 0-9.



92 On the Condensation [1823.

Carbonic Acid. The materials used irf the production of
carbonic acid, were carbonate of ammonia and concentrated
sulphuric acid ; the manipulation was like that described for
sulphuretted hydrogen. Much stronger tubes are however
required for carbonic acid than for any of the former substances,
and there is none which has produced so many or more power-
ful explosions. Tubes which have held fluid carbonic acid
well for two or three weeks together, have, upon some increase
in the warmth of the weather, spontaneously exploded with
great violence ; and the precautions of glass masks, goggles,
&c., which are at all times necessary in pursuing these experi-
ments, are particularly so with carbonic acid.

Carbonic acid is $ limpid colourless body, extremely fluid,
and floating upon the other contents of the tube. It distils
readily and rapidly at the difference of temperature between
32 and 0. Its refractive power is much less than that of
water. No diminution of temperature to which I have been
able to submit it, has altered its appearance. In endeavouring
to open the tubes at one end, they have uniformly burst into
fragments, with powerful explosions. By enclosing a gauge
in a tube in which fluid carbonic acid was afterwards produced,
it was found that its vapour exerted a pressure of 36 atmo-
spheres at a temperature of 32.

It may be questioned, perhaps, whether this and other
similar fluids obtained from materials containing water, do not
contain a portion of that fluid ; inasmuch as its absence has
not been proved, as it may be with chlorine, sulphurous acid,
cyanogen, and ammonia. But besides the analogy which exists
between the latter and the former, it may also be observed in
favour of their dryness, that any diminution of temperature
causes the deposition of a fluid from the atmosphere, precisely
like that previously obtained ; and there is no reason for sup-
posing that these various atmospheres, remaining as they do
in contact with concentrated sulphuric acid, are not as dry as
atmospheres of the same kind would be over sulphuric acid at
common pressure.

Euchlorine. Fluid euchlorine was obtained by enclosing
chlorate of potash and sulphuric acid in a tube, and leaving
them to act on each other for twenty-four hours. In that time
there had been much action, the mixture was of a dark reddish



1823.] of several Gases into Liquids. 93

brown, and the atmosphere of a bright yellow colour. The
mixture was then heated up to 100, and the unoccupied end
of the tube cooled to ; by degrees the mixture lost its dark
colour, and a very fluid ethereal-looking substance condensed.
It was not miscible with a small portion of the sulphuric acid
which lay beneath it ; but when returned on to the mass of
salt and acid, it was gradually absorbed, rendering the mixture
of a much deeper colour even than itself.

Euchlorine thus obtained is a very fluid transparent sub-
stance, of a deep yellow colour. A tube containing a portion
of it in the clean end, was opened at the opposite extremity ;
there was a rush of euchlorine vapour, but the salt plugged
up the aperture: whilst clearing this away, the whole tube
burst with a violent explosion, except the small end in a cloth
in my hand, where the euchlorine previously lay, but the fluid
had all disappeared.

Nitrous Oxide. Some nitrate of ammonia, previously made
as dry as could be by partial decomposition by heat in the
air, was sealed up in a bent tube, and then heated in one end,
the other being preserved cool. By repeating the distillation
once or twice in this way, it was found, on after-examination,
that very little of the salt remained undecomposed. The pro-
cess requires care. I have had many explosions with very
strong tubes, and at considerable risk.

When the tube is cooled, it is found to contain two fluids,
and a very compressed atmosphere. The heavier fluid on ex-
amination proved to be water, with a little acid and nitrous
oxide in solution ; the other was nitrous oxide. It appears in
a very liquid, limpid, colourless state ; and so volatile, that the
warmth of the hand generally makes it disappear in vapour.
The application of ice and salt condenses abundance of it into
the liquid state again. It boils readily by the difference of
temperature between 50 and 0. It does not appear to have
any tendency to solidify at 10. Its refractive power is very
much less than that of water, and less than any fluid that has
yet been obtained in these experiments, or than any known
fluid. A tube being opened in the air, the nitrous oxide im-
mediately burst into vapour. Another tube was opened under
water ; the vapour being collected and examined proved to
be nitrous oxide gas. A gauge being introduced into a tube,



94 On the Condensation [1823.

in which liquid nitrous oxide was afterwards produced, gave the
pressure of its vapour as equal to above 50 atmospheres at 45.

Cyanogen. Some pure cyanuret of mercury was heated
until perfectly dry. A portion was then enclosed in a green
glass tube, in the same manner as in former instances, and
being collected to one end, was decomposed by heat, whilst
the other end was cooled. The cyanogen soon appeared as a
liquid : it was limpid, colourless, and very fluid ; not altering
its state at the temperature of 0. Its refractive power is
rather less, perhaps, than that of water, A tube containing
it being opened in the air, the expansion within did not appear
to be very great ; and the liquid passed with comparative slow-
ness into the state of vapour, producing great cold. The
vapour being collected over mercury, proved to be pure
cyanogen.

A tube was sealed up with cyanuret of mercury at one end,
and a drop of water at the other ; the fluid cyanogen was
then produced in contact with the water. It did not mix, at



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