Copyright
Michael Faraday.

Experimental researches in chemistry and physics online

. (page 11 of 49)
Online LibraryMichael FaradayExperimental researches in chemistry and physics → online text (page 11 of 49)
Font size
QR-code for this ebook


there was no liquid in the tube at common temperatures ; but
when the bend of the tube was cooled to 32 by a little ice,
fluid appeared : a bath of ice and salt caused a still more
abundant condensation. The pressure appeared then to be
above thirty atmospheres, but the motion of the mercury in the
gauge had become obstructed through the action of the fluo-
silicon, and no confidence could be reposed in its indications.

Phosphuretted Hydrogen. This gas was prepared by boil-
ing phosphorus in a strong pure solution of caustic potassa,
and the gas was preserved over water in a dark room for seve-
ral days to cause the deposition of any mere vapour of phos-
phorus which it might contain. It was then subjected to high
pressure in a tube cooled by a carbonic acid bath, which had
itself been cooled under the receiver of the air-pump. The
gas in its way to the pumps passed through a long spiral of
thin narrow glass tube immersed in a mixture of ice and salt at
0, to remove as much water from it as possible.

By these means the phosphuretted hydrogen was liquefied ;
for a pure, clear, colourless, transparent and very limpid fluid
appeared, which could not be solidified by any temperature
applied, and which, when the pressure was taken off, imme-
diately rose again in the form of gas. Still the whole of the
gas was not condensable into this fluid. By working the
pumps the pressure would rise up to twenty-five atmospheres
at this very low temperature, and yet at the pressure of two or
three atmospheres and the same temperature, liquid would
remain. There can be no doubt that phosphuretted hydrogen
condensed ; but neither can there be a doubt that some other
gas, not so condensable, was also present, which perhaps may
be either another phosphuretted hydrogen or hydrogen itself.

Fluoboron. This substance was prepared from fluor spar,
fused boracic acid and strong sulphuric acid, in a tube-gene-



106 On the Liquefaction and Solidification [1844.

rator such as that already described, and conducted into a
condensing tube under the generating pressure. The ordinary
carbonic acid bath did not condense it, but the application of
one cooled under the air-pump caused its liquefaction, and
fluoboron then appeared as a very limpid, colourless, clear fluid,
showing no signs of solidification, but when at the lowest tem-
perature mobile as hot ether. When the pressure was taken
off, or the temperature raised, it returned into the state of gas.
The following are some results of pressure all that I could
obtain with the liquid in my possession ; for, as the liquid is
light and the gas heavy, the former rapidly disappears in pro-
ducing the latter. They make no pretensions to accuracy,
and are given only for general information.

Fahr. Atmospheres.

-100 .. 4-61
- 82 7-5



Fahr. Atmospheres.



-72 . . 9-23
-66 . 10-00



Fahr. Atmospheres.



-62 . . 11-54



The preceding are, as far as I am aware, new results of the
liquefaction and solidification of gases. I will now briefly add
such other information respecting solidification, pressure, &c.,
as I have obtained with gaseous bodies previously condensed.
As to pressure, considerable irregularity often occurred, which
I cannot always refer to its true cause : sometimes a little of
the compressed gas would creep by the mercury in the gauge,
and increase the volume of enclosed air ; and this varied with
different substances, probably by some tendency which the
glass had to favour the condensation of one (by something
analogous to hygrometric action) more than another. But
even when the mercury returned to its place in the gauge,
there were anomalies which seemed to imply, that a substance,
supposed to be one, might be a mixture of two or more. It is,
of course, essential that the gauge be preserved at the same
temperature throughout the observations.

Muriatic Acid. This substance did not freeze at the lowest
temperature to which I could attain. Liquid muriatic acid dis-
solves bitumen; the solution, liberated from pressure, boils,
giving off muriatic acid vapour, and the bitumen is left in a
solid frothy state, and probably altered, in some degree, che-
micallyi The acid unites with and softens the resinous cap



1844.] of Bodies generally existing as Gases.



107



cement, but leaves it when the pressure is diminished. The
following are certain pressures and temperatures, which, I
believe, are not very far from truth ; the marked numbers are
from experiment.



Fahr.


Atmospheres. Fahr.


Atmospheres. Fahr.


Atmospheres.


o




o




o




100


. . 1-80


w-53


v^ 5-83


^- 5


. . 13-88


92


. . 2-28


-50


'.' ] . 6-30


w


. . 15-04


90


. . 2-38


v^-42


. . 7-40


10


. . 17-74


83


. . 2-90


-40


. : ; 7-68


20


. . 21-09


80


. . 3-12


33


. . 8-53


^ 25


. . 23-08


77


. . 3-37


-30


. . 9-22


30


. . 25-32


70


. . 4-02


^-22


. . 10-66


w 32


. . 26-20


67


. . 4-26


-20


. . 10-92


40


. . 30-67


60


. . 5-08


-10


. . 12-82







The result formerly obtained * was forty atmospheres at the
temperature of 50 Fahr.

Sulphurous Acid. When liquid, it dissolves bitumen. It
becomes a crystalline, transparent, colourless, solid body at
105 Fahr. ; when partly frozen the crystals are well formed.
The solid sulphurous acid is heavier than the liquid, and sinks
freely in it. The following is a Table of pressures in atmo-
spheres of 30 inches mercury, of which the marked results are
from many observations, the others are interpolated. They
differ considerably from the results obtained by Bunsen f, but
agree with my first and only result.



Fahr.
o





10



^26
31-5



Fahr.

76-8



85
90
93
98



Atmospheres. Fahr. Atmospheres.

0-725 40 . . 1-78

0-92 46-5 . . 2-00

1-00 v48 . . 2-06

1-12 ^56 . . 2-42

1-23 58 .. 2-50

1-33 ^64 . . 2-76

1-50 68 . . 3-00 104

1-53 w73-5 . . 3-28 110
1-57

Sulphuretted Hydrogen. This substance solidifies at

* Philosophical Transactions, 1823, p. 198; or p. 95.
t Bibliotheque Universelle, 1839, xxiii. p. 185.



Atmospheres .

, 3-50
, 4-00

435

4-50

5-00

5-16

5-50

6-00



108



On the Liquefaction and Solidification [1844.



Fahr. below 0, and is then a white, crystalline, translucent sub-
stance, not remaining clear and transparent in the solid state
like water, carbonic acid, nitrous oxide, &c., but forming a
mass of confused crystals like common salt or nitrate of am-
monia, solidified from the melted state. As it fuses at tempe-
ratures above -122, the solid part sinks freely in the fluid,
indicating that it is considerably heavier. At this temperature
the pressure of its vapour is less than one atmosphere not
more, probably, than 0'8 of an atmosphere, so that the liquid
allowed to evaporate in the air would not solidify as carbonic
acid does.

The following is a Table of the tension of its vapour, the
marked numbers being close to experimental results, and the
rest interpolated. The curve resulting from these numbers,
though coming out nearly identical in different series of experi-
ments, is apparently so different in its character from that of
water or carbonic acid, as to leave doubts on my mind respecting
it, or else of the identity of every portion of the fluid obtained,
yet the crystallization and other characters of the latter seemed
to show that it was a pure substance.



Fahr.


Atmospheres.


Fahr.


Atmospheres.


Fahr.


Atmospheres.


o




o




o




-100


. . 1-02


-50


. . 2-35





. . 6-10


w- 94


. . 1-09


^-45


.. 2-59


10


7-21


w- 90


. . 1-15


^-40


. . 2\S6


20


. . 8-44


w- 83


. . 1-27


-30


. . 3-49


^26


. . 9-36


- 80


. . 1*33


^-24


. . 3-95


30


. . 9-94


74


. . 1-50


w-20


. . 4-24


40


. . 11-84


- 70


. . 1-59


^-16


. . 4-60


v/18


. . 13-70


w_ 68


. . 1-67


-10


-.-. 5-11


50


. . 14-14


- 60


. . 1-93


2


-. i 5-90


^52


. . 14-60


v- 58


. . 2-00











Carbonic Acid. The solidification of carbonic acid by M.
Thilorier is one of the most beautiful experimental results of
modern times. He obtained the substance, as is well known,
in the form of a concrete white mass like fine snow, aggregated.
When it is melted and resolidified by a bath of low tempera-
ture, it then appears as a clear, transparent, cystalline, colour-
less body, like ice; so clear indeed, that at times it was
doubtful to the eye whether anything was in the tube, yet at



1844.] of Bodies generally existing as Gases. 109

the same time the part was filled with solid carbonic acid. It
melts at the temperature of 70 or 72 Fahr., and the solid
carbonic acid is heavier than the fluid bathing it. The solid
or liquid carbonic acid at this temperature has a pressure of
5'33 atmospheres nearly. Hence it is easy to understand the
readiness with which liquid carbonic acid, when allowed to
escape into the air, exerting only a pressure of one atmosphere,
freezes a part of itself by the evaporation of another part.

Thilorier gives 100 C. or 148 Fahr. as the temperature
at which carbonic acid becomes solid. This however is rather
the temperature to which solid carbonic acid can sink by
further evaporation in the air, and is a temperature belonging
to a pressure not only lower than that of 5*33 atmospheres,
but even much below that of one atmosphere. This cooling
effect to temperatures below the boiling-point often appears.
A bath of carbonic acid and ether exposed to the air will cool
a tube containing condensed solid carbonic acid, until the
pressure within the tube is less than one atmosphere ; yet, if
the same bath be covered up so as to have the pressure of one
atmosphere of carbonic acid vapour over it, then the tempera-
ture is such as to produce a pressure of 2'5 atmospheres by
the vapour of the solid carbonic acid within the tube.

The estimates of the pressure of carbonic acid vapour are
sadly at variance ; thus, Thilorier * says it has a pressure of
26 atmospheres at 4 Fahr., whilst Addamsf says that for
that pressure it requires a temperature of 30. Addams gives
the pressure about 27| atmospheres at 32, but Thilorier and
my self t give it as 36 atmospheres at the same temperature.
At 50 Brunei estimates the pressure as 60 atmospheres,
whilst Addams makes it only 34*67 atmospheres. At 86
Thilorier finds the pressure to be 73 atmospheres ; at 4 more,
or 90, Brunei makes it 120 atmospheres ; and at 10 more, or
100, Addams makes it less than Thilorier at 86, and only
62*32 atmospheres ; even at 150 the pressure with him is not
quite 100 atmospheres.

I am inclined to think that at about 90 Cagniard de la
Tour's state comes on with carbonic acid. From Thilorier's
data we may obtain the specific gravity of the liquid and the

Ann. de Chim. 1835, Ix. 427, 432. f Report of Brit. Assoc. 1838, p. 70.
J Phil. Trans, 1823, p, 193. Royal Institution Journal, xxi, 132.



no



On the Liquefaction and Solidification [1844.



vapour over it at the temperature of 86 Fahr., and the former
is little more than twice that of the latter ; hence a few degrees
more of temperature would bring them together, and Brunei's
result seems to imply that the state was then on, but in that
case Addams's results could only be accounted for by supposing
that there was a deficiency of carbonic acid. The following
are the pressures which I have recently obtained :



Fahr;


Atmospheres.


Fahr.


Atmospheres.


Fahr.


Atmospheres.


w-llf


. . 1-14


-60


. . 6-97


- 4


. . 21-48


-110


. . 1-17


w_56


. . 7-70





. . 22-84


^-107


. . 1-36


-50


. . 8-88


^ 5


. . 24-75


-100


. . 1-85


-40


. . 11-07


^ 10


. . 26-82


95


. . 2'28


w-34


. . 12-50


w 15


. . 29-09


- 90


. . 2*77


-SO


. . 13-54


20


. . 30-65


v- 83


. . 3-60


23


. . 15-45


^ 23


. . 33-15


- 80


. . 3-93


-20


. . 16-30


30


. . 37-19


w- 75


. . 4-60


15


. . 17-80


^ 32


. . 38-50


- 70


. . 5-33


-10


. . 19-38







Carbonic acid is remarkable amongst bodies for the high
tension of the vapour which it gives off whilst in the solid or
glacial state. There is no other substance which at all comes
near it in this respect, and it causes an inversion of what in all
other cases is the natural order of events. Thus, if, as is the
case with water, ether, mercury or any other fluid, that tem-
perature at which carbonic acid gives off vapour equal in
elastic force to one atmosphere, be called its boiling-point ; or,
if (to produce the actual effect of ebullition) the carbonic acid
be plunged below the surface of alcohol or ether, then we
shall perceive that the freezing and boiling points are inverted,
i. e. that the freezing-point is the hotter, and the boiling-point
the colder of the two, the latter being about 50 below the
former.

Euchlorine. This substance was easily converted from the
gaseous state into a solid crystalline body, which, by a little
increase of temperature, melted into an orange-red fluid, and
by diminution of temperature again congealed ; the solid eu-
chlorine had the colour and general appearance of bichromate
of potassa; it was moderately hard, brittle and translucent;
and the crystals were perfectly clear. It melted at the tempe-



1844.] of Bodies generally existing as Gases. Ill

rature of 75 below 0, and the solid portion was heavier than
the liquid.

When in the solid state it gives off so little vapour, that the
eye is not sensible of its presence by any degree of colour in
the air over it when looking down a tube 4 inches in length,
at the bottom of which is the substance. Hence the pressure
of its vapour at that temperature must be very small.

Some hours after, wishing to solidify the same portion of
euchlorine which was then in a liquid state, I placed the tube
in a bath at 1 10, but could not succeed, either by continuance
of the tube in the bath, or shaking the fluid in the tube, or
opening the tube to allow the full pressure of the atmosphere ;
but when the liquid euchlorine was touched by a platinum wire
it instantly became solid, and exhibited all the properties before
described. There are many similar instances amongst ordinary
substances, but the effect in this case makes me hesitate in con-
cluding that all the gases which as yet have refused to solidify
at temperatures as low as 166 below 0, cannot acquire the
solid state at such a temperature.

Nitrous Oxide. This substance was obtained solid by the
temperature of the carbonic acid bath in vacuo, and appeared
as a beautiful clear crystalline colourless body. The tempera-
ture required for this effect must have been very nearly the
lowest, perhaps about 150 below 0. The pressure of the
vapour rising from the solid nitrous oxide was less than one
atmosphere.

Hence it was concluded that liquid nitrous oxide could not
freeze itself by evaporation at one atmosphere, as carbonic acid
does ; and this was found to be true, for when a tube containing
much liquid was freely opened, so as to allow evaporation down
to one atmosphere, the liquid boiled and cooled itself, but
remained a liquid. The cold produced by the evaporation was
very great, and this was shown by putting the part of the tube
containing the liquid nitrous oxide, into a cold bath of carbonic
acid, for the latter was like a hot bath to the former, and
instantly made it boil rapidly.

I kept this substance for some weeks in a tube closed by
stopcocks and cemented caps. In that time there was no
action on the bitumen of the graduation, nor on the cement of
the caps ; these bodies remained perfectly unaltered*



112 On the Liquefaction and Solidification [1844.

Hence it is probable that this substance may be used in
certain cases, instead of carbonic acid, to produce degrees of
cold far below those which the latter body can supply. Down
to a certain temperature, that of its solidification, it would not
even require ether to give contact, and below that temperature
it could easily be used mingled with ether ; its vapour would
do no harm to an air-pump, and there is no doubt that the
substance placed in vacuo would acquire a temperature lower
than any as yet known, perhaps as far below the carbonic acid
bath in vacuo as that is below the same bath in air.

This substance, like olefiant gas, gave very uncertain results
at different times as to the pressure of its vapour; results
which can only be accounted for by supposing that there are
two different bodies present, soluble in each other, but differing
in the elasticity of their vapour. Four different portions gave
at the same temperature, namely 106 Fahr., the following
great differences in pressure : 1 '66 ; 4*4 ; 5*0 ; and 6*3 atmo-
spheres ; and this after the elastic atmosphere left in the tubes
at the conclusion of the condensation had been allowed to
escape, and be replaced by a portion of the respective liquids
which then rose in vapour. The following Table gives certain
results with a portion of liquid which exerted a pressure of six
atmospheres at 106 Fahr.

Fahr. Atmospheres. Atmospheres.

-40 . . . 10-20
-35 . . . 10-95
-30 . . . 11-80
-25 . . . 12-75
-20 ... 13-80
-15 ... 14-95
-10 ... 16-20
- 5 ... 17-55

... 19-05 . . . 24-40
5 ... 20-70 . . . 26-08
10 ... 22-50 . . . 27-84
15 ... 24-45 . . . 29-68
20 ... 26-55 . . . 31-62
25 ... 28-85 . . . 33-66
30 ... ... 35-82

35 . 38-10



1844.] of Bodies generally existing as Gases* 113

The second column expresses the pressures given as the
fluid was raised from low to higher temperatures. The third
column shows the pressures given the next day with the same
tube after it had attained to and continued at the atmospheric
temperature for some hours. There is a difference of four or
five atmospheres between the two, showing that in the first
instance the previous low temperature had caused the solution
of a more volatile part in the less volatile and liquid portion,
and that the prolonged application of a higher temperature
during the night had gradually raised it again in vapour. This
result occurred again and again with the same specimen*.

Cyanogen. This substance becomes a solid transparent
crystalline body, as Bunsen has already stated f, which raised
to the temperature of 30 Fahr. then liquefies. The solid
and liquid appear to be nearly of the same specific gravity, but
the solid is perhaps the denser of the two.

The mixed solid and liquid substance yields a vapour of
rather less pressure than one atmosphere. In accordance
with this result, if the liquid be exposed to the air, it does not
freeze itself as carbonic acid does.

The liquid tends to distil over and condense on the cap
cement and bitumen of the gauge, but only slightly. When
cyanogen is made from cyanide of mercury sealed up hermeti-
cally in a glass tube, the cyanogen distils back and condenses
in the paracyanic residue of the distillation ; but the pressure
of the vapour at common temperatures is still as great, or very
nearly so, as if -the cyanogen were in a clean separate liquid
state.

A measured portion of liquid cyanogen was allowed to
escape and expand into gas. In this way one volume of liquid
at the temperature of 63 Fahr. gave 393*9 volumes of gas at
the same temperature and the barometric pressure of 3O2
inches. If 100 cubic inches of the gas be admitted to weigh

* This substance is one of those which I liquefied in 1823 (see Philosophical
Transactions). Since writing the above, I perceive that M. Natterer has con-
densed it into the liquid state by the use of pumps only (see Comptes Rendus,
1844, Nov. 18, p. 1111), and obtained the liquid in considerable quantities.
The non-solidification of it by exposure to the air perfectly accords with my
own results.

t Bibliotheque Universelle, 1839, xxiii, p. 184.

I



114 On the Liquefaction and Solidification [1844.

55*5 grains, then a cubic inch of the liquid would weigh 218*6
grains. This gives its specific gravity as 0*866. When first
condensed, I estimated it as nearly 0*9.

Cyanogen is a substance which yielded on different occasions
results of vaporous tension differing much from each other,
though the substance appeared always to be pure. The fol-
lowing are numbers in which I place some confidence, the
pressures being in atmospheres of 30 inches of mercury, and
the marked results experimental *.

Fahr.



8-5

-10

15

-20

22-8
-27
-32
34-5

Ammonia. This body may be obtained as a solid, white,
translucent, crystalline substance, melting at the temperature
of 1 03 below ; at which point the solid substance is heavier
than the liquid. In that state the pressure of its vapour must
be very small.

Liquid ammonia at 60 was allowed to expand into ammo-
niacal gas at the same temperature ; one volume of the liquid
gave 1009*8 volumes of the gas, the barometer being at the
.pressure of 30'2 inches. If 100 cubic inches of ammoniacal
gas be allowed to weigh 18*28 grains, it will give 184*6 grains
as the weight of a cubic inch of liquid ammonia at 60. Hence
its specific gravity at that temperature will be 0*731. In the
old experiments I found by another kind of process that its
specific gravity was 0*76 at 50.

The following is a Table of the pressure of ammonia vapour,
the marked results, as before, being those obtained by experi-
ment :



Atmospheres.


Fahr.


Atmospheres.


Fahr.


Atmospheres.


1-25


-385


. 2*72


77 .


. 5-00


1*50


-44-5 .


. 3*00


- 79 .


. 5-16


1-53


-48 , *


. 3-17


83 ,,. ?


. 5-50


1*72


v>50 , .-


. 3-28


88-3.


. 6*00


1*89


-52 .


. 3-36


- 93-5 .


. 6*50


2-00


54-3 .


. 3*50


- 95 .


. 6*64


2*20


-63 .


. 4*00


98*4.


. 7-00


2*37


-70 .


. 4*50


-103 .


. 7*50


2-50


-74


4*79







See Bunsen's results, Bibliotheque Universelle, 1839, xxiii. p. 185.



J 844-.] of Bodies generally existing as Gases.



115



Fahr.


Atmospheres.


Fahr.


00 .


. 2-48


-41


0-5 .


. 2-50


-44


-9-3 .


. 3-00


-45


-18 ^


. 3-50


45-8


-21 .


. 3-72


-49


25-8 .


. 4-00


-51-4


-26


. 4-04


-52


-32 .


. 4-44


-55


-33 .


. 4-50


-56-5


39-5 .


. 5-00


-60



Atmospheres.


Fahr.


Atmospheres.


5-10


-81-3 .


. 7-00


5-36


-85-6 .


. 7-50


5-45


-67 .


. 7-63


5-50


69-4 .


. 8-00


5-83


73 ;


. 8-50


6-00


76-8 .


. 9-00


6-10


80 -.


. 9-50


6-38


-83 ' .


. 10-00


6-50


85 ; .


. 10-30


6-90







Arseniuretled Hydrogen. This body, liquefied by Dumas
and Soubeiran, did not solidify at the lowest temperature to
which I could submit it, i. e. not at 166 below Fahr. In
the following Table of the elasticity of its vapour the marked
results are experimental, and the others interpolated :



Fahr.



Atmospheres.


Fahr.


Atmospheres.


Fahr.


Atmospheres.


. 0-94


-30


. . 2-84


-10


. 6-24


. 1-08


23


. . 3-32


-20


. . 7-39


. 1-26


-20


. . 3-51


30


. . 8-66


. 1-40


-10


. . 4-30


-32


. . 8-95


. 1-73


w 5


. . 4-74


-40


. . 10-05


. 1-80


-


. . 5-21


-50


. . 11-56


. 2-28


- 3


. . 5-56


-60


. . 13-19


. 2-50











-60

52

-50

-40

- 36



The following bodies would not freeze at the very low
temperature of the carbonic acid bath in vacuo ( 166 Fahr.):
Chlorine, ether, alcohol, sulphuret of carbon, caoutchoucine,
camphine or rectified oil of turpentine. The alcohol, caout-
choucine and camphine lost fluidity and thickened somewhat
at 106, and still more at the lower temperature of 166.
The alcohol then poured from side to side like an oil.

Dry yellow fluid nitrous acid when cooled below loses the
greater part of its colour, and then fuses into a white, cry-
stalline, brittle and but slightly translucent substance, which
fuses a little above Fahr. The green and probably hy-
drated acid required a much lower temperature for its solidifi-
cation, and then became a pale bluish solid. There were then

I 2



116 On the Liquefaction and Solidification [1844.

evidently two bodies, the dry acid which froze out first, and
then the hydrate, which requires at least 30 below before
it will solidify.

The following gases showed no signs of liquefaction when
cooled by the carbonic acid bath in vacuo, even at the pressures

expressed :

Atmospheres.

Hydrogen at ... . . . 27

Oxygen ........ 7

Nitrogen . 50

Nitric oxide ... . . . 50



Online LibraryMichael FaradayExperimental researches in chemistry and physics → online text (page 11 of 49)