weight of water being added and heated, the whole was dissolved,
and on cooling, a salt, consisting of extremely minute filaments
resembling asbestos, was obtained, which, by capillary attraction,
retained a part of the residual solution so powerfully, that it was
necessary to absorb it by filtering paper.
Although it appeared improbable that the crystals could be a variety
of the known form of bisulphate of potash, yet supposing it might
be that salt with either less, or more than two atoms of water, Mr.
Phillips proceeded to its analysis. Some of the salt was readily
dried by exposure to the air of a warm room: 100 grains, by muriate
of baryta gave 154.75 grains of sulphate of baryta, equivalent
to 52.45 sulphuric acid: 109 grains heated to redness, lost 21.6
sulphuric acid and water, and left 78.4 grains of neutral sulphate
of potash. The latter contain 35.6 grains of sulphuric acid, which,
subtracted from the whole quantity of 52.45, indicates 16.85 as the
quantity dissipated by heat; and this again, subtracted from the
21.6, indicates 4.75 water in the crystals. The quantity of acid
separated by heat is, therefore, very nearly half that remaining
in the neutral sulphate, and the salt in question appears to be a
sesquisulphate of potash, consisting of
theory. experiment.
3 atoms sulphuric acid 120 55.33 52.45
2 " potash 96 42.66 42.80
1 atom water 9 4.00 4.75
--- ----- ------
225 99.99 100.00
Mr. Phillips found it difficult to prepare the sesquisulphate free
[p468] from bisulphate; and on repeating the attempt to procure it
exactly as before, obtained a large quantity of bisulphate, and a
small quantity of the peculiar salt; although the quantity of water
present is known to have an important influence on the nature of
the sulphates produced, yet the precise circumstances on which the
formation of sesquisulphate depends, are at present unknown.—_Phil.
Mag. N. S._, ii. 429.
10. _On certain Properties of Sulphur_.—The effect of heat upon
sulphur in first fusing it, but afterwards causing diminution of
fluidity in a certain degree proportionate to the temperature, has
been long and generally known, as well also as the peculiar soft
state into which the sulphur may be brought, by pouring it, when hot
and thickened, into cold water. M. Dumas has been led to examine
these phenomena for the purpose of acquiring a precise and particular
knowledge of the effects and changes.
Fused sulphur began to crystallize between 226° and 228°. Its fusing
point may be considered as 226°.4. Between 230° and 284° it is as
liquid as a clear varnish, and of the colour of amber; at about 320°
it begins to thicken, and acquire a red colour; on increasing the
heat, it becomes so thick, that it will not pour. This effect is most
marked between 428° and 572°; the colour being then a red-brown. From
572° to the boiling point it becomes thinner, but never so fluid as
at 248°. The deep red-brown colour continues until it boils.
When the most fluid sulphur is suddenly cooled, it becomes brittle,
but the thickened sulphur, similarly treated, remains soft, and more
soft as the temperature has been higher. Thus, at 230°, the sulphur
was very liquid, and yellow; and cooled suddenly by immersion in
water, it became yellow and very friable; at 374° it was thick,
and of an orange colour, but by cooling, became at first soft and
transparent, but soon friable, and of the ordinary appearance; at
428°, it was red and viscid, and when cooled, soft, transparent,
and of an amber colour; at the boiling point it was deep brown red
colour, and when cooled very soft, transparent, and of a red-brown
colour.
It is not necessary, as is sometimes stated, to heat the sulphur a
long time to produce this effect; all depends upon temperature. The
only precaution necessary is, to have abundance of water, and to
divide the sulphur into small drops or portions, that the cooling may
be rapid. If it be poured in a mass, the interior cools slowly, and
acquires the ordinary hard state. When the experiment is well made at
446°, the sulphur may be drawn into threads as fine as a hair, and
many feet in length.
M. Dumas, in remarking upon this curious effect of sudden cooling,
classes it with the similar effect which occurs with bronze. Although
difficult to assign the exact cause, yet he notices that the tendency
to crystallize can evidently be traced as influential over some of
the appearances, the hardness and opacity, for instance, [p469]
which always occur together when the crystalline state is assumed;
whereas, when rapid cooling has hindered crystallization, the mass
remains soft and transparent, until it crystallizes, which usually
happens in twenty or thirty hours.—_Ann. de Chimie_, xxxvi. 83.
11. _On the Fluidity of Sulphur and Phosphorus at common
temperatures_, by Mr. Faraday.—I published some time ago a short
account of an instance of the existence of fluid sulphur at common
temperatures[130]; and though I thought the fact curious, I did not
esteem it of such importance as to put more than my initials to
the account. I have just learned, through the _Bulletin Universel_
for September, p. 178[131], that Signor Bellani had observed the
same fact in 1813, and published it in the _Giornale di Fisica_,
vol. vi. (old series). I also learn, by the same means, that M.
Bellani complains of the manner in which facts and theories, which
have been published by him, are afterwards given by others as new
discoveries; and though I find myself classed with Gay-Lussac, Sir
H. Davy, Daniell, Bostock, &c., in having thus erred, I shall not
rest satisfied, without making restitution, for M. Bellani, in this
instance, certainly deserves it at my hand.
Not being able to obtain access to the original journal, I shall
quote M. Bellani’s very curious experiments from the Bulletin, in
which they appear to be fully described. “The property which water
possesses, of retaining its fluid states, when in tranquillity, at
temperatures 10° or 15° below its freezing point, is well known;
phosphorus behaves in the same manner; sometimes its fluidity may
be retained at 13° (centigrade?) for a minute, an hour, or even
many days. What is singular is, that, though water cooled below
its freezing point, congeals easily upon slight internal movement,
however communicated, phosphorus, on the contrary, sometimes retains
its liquid state even at 3°, even though it be shaken in a tube or
poured upon cold water. But, as soon as it has acquired the lowest
temperature which it can bear without solidifying, the moment it
is touched with a body at the same temperature, it solidifies so
quickly, that the touching body cannot penetrate its mass. If the
smallest morsel of phosphorus is put into contact with a liquified
portion, the latter infallibly solidifies, though it be only a single
degree below the limit of temperature necessary; this does not always
happen when the body touching it is heterogeneous.
“Sulphur presented the same phenomena as phosphorus; fragments of
sulphur always produced the crystallization of cold fluid portions.
Having withdrawn the bulb of a thermometer which had been plunged
into sulphur at 120°, it came out covered with small globules of
sulphur, which remained fluid at 60°; and having touched these one
after another with a thread of glass, they became solid: although
several seemed in contact, yet it required that each [p470] should
be touched separately. A drop of sulphur, which was made to move
on the bulb of the thermometer, by turning the instrument in a
horizontal position, did not congeal until nearly at 30°; and some
drops were retained fluid at 15°, _i. e._ 75° of Reaumur below the
ordinary point of liquefaction.”
The _Bulletin Universel_ then proceeds to describe some late and new
experiments of M. Bellani, on the expansion in volume of a cold dense
solution of sulphate of soda during the solidification of part of the
salt in it. The general fact has, however, been long and well known
in this country and in France; and the particular form of experiment
described is with us a common lecture illustration. The expansion, as
ascertained by M. Bellani, is 2/87 of the original volume of fluid.
According to the Bulletin, M. Bellani also claims, though certainly
in a much less decided manner than the above, the principal ideas
in a paper which I have published on the existence of a limit to
vaporization, and I referred back to the _Giornale di Fisica_ for
1822, (published prior to my paper,) for the purpose of rendering
justice in this case also. Here, however, the contact of our ideas
is so slight, and for so brief a time, that I shall leave the papers
in the hands of the public without further remarks. It is rather
curious to observe how our thoughts had been at the same time upon
the same subject. Being charged in the Bulletin with quoting an
experiment from a particular page in M. Bellani’s memoir, (which
I did from another journal, in which the experiment only was
described,) I turned to the original place, and there, though I found
the experiment I had transferred, I also found another which I had
previously made on the same subject, and which M. Bellani had quoted.
I very fully join in the regret which the _Bulletin Universel_
expresses, that scientific men do not know more perfectly what has
been done, or what their companions are doing; but I am afraid the
misfortune is inevitable. It is certainly impossible for any person
who wishes to devote a portion of his time to chemical experiment, to
read all the books and papers that are published in connexion with
his pursuit; their number is immense, and the labour of winnowing out
the few experimental and theoretical truths which in many of them
are embarrassed by a very large proportion of uninteresting matter,
of imagination, and of error, is such, that most persons who try the
experiment are quickly induced to make a selection in their reading,
and thus inadvertently, at times, pass by what is really good.
FOOTNOTES:
[130] Quarterly Journal of Science, xxi. 392.
[131] The Italian Journal has not yet arrived in this country.
12. _Separation of Selenium from Sulphur_.—Berzelius says, that
these substances, so much resembling each other in their general
properties, may be easily separated by the following process. When
sulphuret of selenium is fused with carbonate of potash, the alkali
not being excess, the fused mass, dissolved in water, leaves selenium
undissolved and free from sulphur. [p471]
Some of the sulphuret of selenium from Lukawitz, in Bohemia, was
dissolved in potash, and the solution converted into hyposulphite
by exposure to the air at the temperature of 65° F.; 0.1125 of the
sulphuret experimented with were precipitated, and found to be _pure
selenium_. The solution being of a deeper red colour than that of the
common sulphuret, a piece of sulphur was put into it, and the whole
boiled for a moment; a quarter of a grain of selenium, perfectly free
from sulphur, was precipitated.
A solution of a neutral seleniate, or of one with excess of base,
is soon rendered turbid by having sulphuretted hydrogen passed
through it. At first pure selenium separates; afterwards sulphuret
of selenium; and, lastly, mere sulphur. The solution should be
considerably diluted; when concentrated, the precipitate formed
is of a flame yellow colour, but soon becomes brownish-black, and
sulphur is deposited, sometimes crystallizing at the surface of the
deposite.—_Phil. Mag., N. S._, ii. 390.
13. _On a new Compound of Selenium and Oxygen—Selenic Acid, by_
MM. Mitscherlich and Nitzsch.—This acid contains half as much more
oxygen as that discovered by M. Berzelius, and with potash forms a
neutral salt, having the same form and optical properties as sulphate
of potash, containing no water when crystallized, and producing
insoluble precipitates with barytic salts. The acid is isomorphous
with the sulphuric, and may with propriety be called _selenic acid_,
that described by M. Berzelius being considered as the _selenious
acid_.
The new acid is easily prepared: for this purpose selenium, selenious
acid, a selenite or a metallic selenuret is to be fused with nitre.
Selenuret of lead, being the most abundant source, has been used for
this purpose, but being accompanied by sulphuret, the selenic acid
is usually contaminated by sulphuric acid. The selenuret of lead
is to be freed from carbonates by muriatic acid, and the residue
mixed with its weight of nitrate of soda, and thrown gradually into
a red-hot crucible. Water then dissolves out seleniate nitrate and
nitrite of soda, no selenium remaining in the residue. The solution
quickly boiled, deposits anhydrous seleniate of soda, and this being
separated, by cooling crystals of nitrate of soda are formed; these
being removed, ebullition again causes more seleniate to fall down,
and proceeding in this way an imperfect separation is effected. The
seleniate, like the sulphate of soda, is most soluble in water at
181°. To purify the salt completely, the nitrite should be changed
into nitrate by nitric acid; but then sulphate of soda would remain
as an impurity formed from sulphuret in the ore, and no attempt to
separate this has as yet succeeded.
But if the seleniate of soda be mixed with muriate of ammonia and
heated, selenium, nitrogen and water come over, no trace of sulphur
appearing. The selenium may, however, be dissolved in excess of
nitric acid, and the selenious acid produced tested by [p472]
muriate of baryta, which would then separate sulphuric acid if
present; the clear solution is to be saturated with carbonate of
soda, evaporated to dryness, and the mixture of selenite and nitrate
of soda obtained, fuzed in a porcelain crucible over a spirit-lamp.
Then proceed by crystallization as before, and a pure seleniate of
soda will be produced.
To separate the selenic acid, the solution is to be decomposed
by nitrate of lead; the seleniate of lead is as insoluble as the
sulphate, and being well washed, is to be decomposed by a current
of sulphuretted hydrogen, which has no action on the selenic acid;
the solution being filtered, is to be boiled, and is then diluted
selenic acid. Its purity, as respects fixed bodies, is ascertained
by its entire volatility; if sulphuric acid be present, it may be
ascertained by boiling a portion with muriatic acid, which produces
selenious acid, and then testing by muriate of baryta, a precipitate
indicates sulphuric acid.
From the isomorphism of selenic acid and its salts with sulphuric
acid and its salts, M. Mitscherlich concluded, that the oxygen in the
acid should be to that in selenious acid as 3 to 2; and to that in
bases when it forms salt, as 3 to 1. These views were confirmed by
experiments. From the decomposition of seleniate of potash by muriate
of baryta, it appeared that the seleniate was composed of
Potash 42.16 oxygen 7.15
Selenic acid 57.84 ---- 21.79
------
100.00
The composition of the acid was determined by boiling a certain
weight of the seleniate of soda with muriatic acid in excess, and
decomposing the selenious acid formed by sulphite of soda; 4.88 of
the salt gave 2.02 of selenium, from which, and the above result, it
would appear that the acid is formed of
Selenium 61.4
Oxygen 38.6
-----
100.0
According to Berzelius, selenious acid consists of 100 selenium, and
40.33 oxygen; and supposing this contains two-thirds the oxygen in
selenic acid, the latter should consist of 62.32 and 37.68. From the
analysis above given of the seleniate of potash, it is evident that
100 of selenic acid saturates a quantity of base captaining 12.56 of
oxygen, which would agree with the latter estimate of selenic acid.
_Selenic acid_ is a colourless liquid, which may be heated to 536°,
without sensible decomposition; above that it changes, and is,
rapidly resolved into oxygen and selenious acid at 554°. Heated to
329°, its specific gravity is 2.524; at 512°.6 it is 2.6; at 509°
it is 2.625; but by that time selenious acid has been formed in it.
A portion of concentrated acid, from which the selenious acid had
[p473] been removed, consisted of 84.21 selenic acid, and 15.75
water; but it is certain that the selenic acid begins to decompose
before it has resigned the last portions of water.
Selenic acid has a powerful attraction for water, and evolves much
heat when mixed with it. It is not decomposed by sulphuretted
hydrogen; so that the latter body may be used to decompose the
seleniates of lead and copper. When boiled with muriatic acid it
produces selenious acid and chlorine, and the mixture, like aqua
regia, will dissolve gold or platina. Selenic acid dissolves zinc
and iron, evolving hydrogen; it dissolves copper, evolving selenious
acid; and it dissolves gold, but not platina. Sulphurous acid has no
action on selenic acid, but instantly decomposes the selenious acid.
A solution containing selenic acid is easily decomposed, by first
boiling it with muriatic acid, and then adding sulphurous acid.
Selenic acid is but little inferior to sulphuric acid in its affinity
for bases; seleniate of baryta is not completely decomposed by
sulphuric acid. Its combinations being isomorphous with those of
sulphuric acid, and possessing the same crystalline forms, and the
same general chemical properties, present but very slight, though
very interesting differences from the sulphates. These will be
resumed by M. Mitscherlich in a future memoir, with the express
object of illustrating the theory of Isomorphism.—_Ann. de Chimie_,
xxxvi. 100.
14. _Preparation of Hyposulphuric Acid_.—According to M. Heeren, to
obtain the greatest quantity of this acid in the process of passing
sulphurous acid over black oxide of manganese, the temperature
should be low, and the oxide finely divided. The largest portion of
hyposulphuric acid is formed at the commencement of the operation.
15. _Singular Habitude of Phosphoric Acid with Albumen_.—MM.
Berzelius and Englehart differed in their results respecting the
effect of phosphoric acid on albumen; the latter found the acid
caused precipitation of the substance, the former the reverse.
Fortunately coming into company, they made some experiments, and
discovered a very singular property of the acid. The acid in
Berzelius’s laboratory not precipitating albumen, Dr. Englehart
prepared a fresh portion from phosphorus and nitric acid, evaporating
the solution in a platina vessel, and heating it to redness. This
acid, dissolved in water, precipitated both animal and vegetable
albumen abundantly. Another portion of acid, prepared by burning
phosphorus in air, also precipitated albumen. After many experiments
to discover the cause of difference in the acids, Dr. Englehart
remarked, that the two acids he had prepared, gradually lost their
power of precipitating albumen, and in some days were like the acid
of Berzelius. This change took place both in open and closed vessels,
and was not at all hastened by ebullition. [p474] Upon evaporating
the acid, and heating it to redness, it recovered its precipitating
power, but gradually lost it again by a day’s repose. The cause of
this difference escaped detection; it evidently does not depend upon
a difference of oxidation. “May it not be supposed,” says Berzelius,
“that there exists a chemical combination of phosphoric acid with
water, which is not formed until some time after solution, and which
is incapable of precipitating albumen?”—_Annales de Chimie_, xxxvi.
110.
16. _Economical Preparation of Deutoxide of Barium_.—This process is
due to M. Quesneville. Nitrate of baryta is to be put into a luted
earthenware retort, to which a tube is to be attached for the purpose
of conveying the liberated gases to a water-trough. The retort is
to be gradually heated to redness, and retained at that temperature
as long as nitrous acid and azotic gas pass over; the evolution of
these substances indicates that nitrate of baryta still remains to
be decomposed, but the instant that pure oxygen gas passes off, the
fire is to be removed and the retort cooled. The product of this
decomposition is a peroxide of barium; it falls to pieces in water,
without producing heat, disengages oxygen when boiled with water,
and is reduced to a protoxide by a strong heat. When acted upon by
sulphuric acid, no nitric acid was evolved; and when subjected to
nitric acid, no nitric oxide was produced. The production of this
peroxide is easily understood, for the protoxide formed by the
decomposition of the nitrate being in contact, at a red heat, with a
large quantity of oxygen in a nascent state, combines with it, and is
retained, unless the heat be so high as to decompose it.—_Annales de
Chimie_, xxxvi. 108.
The decomposition and effect are precisely the same as those lately
pointed out by Mr. Phillips as occurring with potassium when the
nitrate of potash is decomposed by heat.—See p. 483 of the last
volume of this Journal.
17. _Preparation of Aluminum—Chloride of Aluminum_.—According to
the accounts published, the following process has succeeded in
the hands of M. Oersted, in decomposing alumina and evolving the
base _aluminum_. Pure alumina is to be heated to redness, and then
well mixed with pulverized charcoal; the mixture is to be placed
in a porcelain tube, and being heated to redness, is to have dry
chlorine gas passed over it; the charcoal reduces the alumina, the
base combines with the chlorine, and oxide of carbon is formed.
The chloride of aluminum is soft, crystalline, and evaporates at
a temperature a little above 212° Fahrenheit: it readily attracts
moisture from the atmosphere, and becomes hot when water is added
to it. Being mixed with an amalgam of potassium, containing much
of the latter metal, and immediately heated, chloride of potassium
is formed, and the metallic base of the alumina combines with the
mercury. The amalgam quickly oxidises by exposure to air; but being
heated out of contact with the atmosphere, the mercury is [p475]
volatilized, and a metallic button is left, having the colour and
splendour of tin. A fuller account of the researches of M. Oersted on
this subject is expected.—Hensmann’s _Repertoire—Phil. Mag. N. S._ ii.
18. _Mutual Action of Lime and Litharge_.—M. Fournet heated a
mixture consisting of 7.12 parts of calcined lime, and 27.89 parts
of litharge, very strongly; a coherent mass was obtained, which,
pulverized and digested in water, gave, when filtered, a perfectly
clear and colourless liquor, which, when treated with sulphuretted
hydrogen, threw down an abundant black precipitate: hence oxide of
lead is rendered soluble in water by means of lime.—_Ann. des Mines_,
i. 538.
19. _New Chloride of Manganese discovered by_ M. J. Dumas.—This
chloride corresponds in proportions to the manganesic acid, and in
contact with water, produces muriatic and manganesic acids. It is
easily obtained by putting a solution of manganesic acid into contact
with concentrated sulphuric acid, and fused common salt. Water and
the new chloride are formed; the former is retained by the acid, the
latter volatilizes in a gaseous form. The body does not, however,
appear to constitute a permanent gas[132], for though, when produced,
it appears as an elastic fluid having a cupreous or greenish tint,
yet when passed into a tube, cooled to 5° or 4° Fahrenheit, it
condenses into a liquid of a brownish green colour.
When the perchloride is produced in a large tube, its vapour
gradually displaces the air present, and the tube becomes filled
with it; if it then be poured into a jar with moistened sides, the
colour of the gas changes as it comes into contact with the moist
air; a thick smoke of a fine rose colour appears; and the sides of
the vessel acquire a deep purple colour due to the manganesic acid
formed. The water thus coloured is abundantly precipitated by nitrate
of silver, and, acted upon by a solution of potash, produces all the
changes of the mineral chamelion.