CHEMISTRY AND PHYSICS.
CHEMISTRY AND PHYSICS,
MICHAEL FARADAY, D.C.L., F.R.S.,
FULLERIAN PROFESSOR OF CHEMISTRY IN THE ROYAL INSTITUTION OF GREAT BRITAIN.
HON. MEM. R.S.ED., CAMB. PHIL., AND MED. CHIRURG. 8OCC., P.G.S., ORD. BORU8SI " POUR
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EEPRINTED FROM THE PHILOSOPHICAL TRANSACTIONS OP 1821 1857 ;
THE JOURNAL OP THE ROYAL INSTITUTION; THE PHILOSOPHICAL MAGAZINE,
AND OTHER PUBLICATIONS.
RICHARD TAYLOR AND WILLIAM FRANCIS,
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PRINTED BY TAYLOR AND FRANCIS,
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THE reasons which induce me to gather together in
this Volume the various physical and chemical papers
scattered in the Philosophical Transactions and else-
where, are the same as those which caused the ' Experi-
mental Researches in Electricity ' to be collected into one
Series. As investigations, several of them are very
imperfect ; but it was thought a duty to print them just
as they were, that they might be referred to as safely for
facts, opinions, and dates, as the original papers. The
correction of certain phrases and typographical errors,
and the addition of some matter here and there with its
proper date, is not considered as interfering with this
C O N T E N T S.
Analysis of native caustic lime ,v r ' 1
Escape of gases through capillary tubes 5
Passage of gases through tubes 6
Combustion of the diamond 11
Apparatus for the combustion of the diamond 11
Oxide of silver in ammonia 13
Combinations of ammonia with chlorides 18
Sounds produced by flame in tubes 21
Action of boracic acid on turmeric . 27
Change of vegetable colours as an alkaline property 29
Action of salts on turmeric paper ...;..... v . ....... 31
Decomposition of chloride of silver by hydrogen and by zinc .... 31
Two new compounds of chlorine and carbon, &c 33
New compound of chlorine and carbon (Phillips and Faraday) . . 53
Vapour of mercury at common temperatures 57
Alloys of steel (Stodart and Faraday) 57
Hydriodide of carbon 81
Hydrate of chlorine 81
Fluid chlorine 85
Condensation of several gases into liquids 89
Liquefaction and solidification of bodies generally existing as gases 96
Historical statement liquefaction of gases 1 24
History of the condensation of gases 1 35
Change of musket balls in Shrapnell shells 141
Action of gunpowder on lead 142
Purple tint of plate-glass affected by light 142
Cases of the formation of ammonia 143
Substitution of tubes for bottles 152
Composition of crystals of sulphate of soda 1 53
New compounds of carbon and hydrogen 154
Pure caoutchouc 1 74
Mutual action of sulphuric acid and naphthaline 182
Existence of a limit to vaporization 1 91>
Limits of vaporization 205
Fluidity of sulphur at common temperatures 212
Fluidity of sulphur and phosphorus at common temperatures .... 213
Perspective aerial light and shadow 215
Confinement of dry gases over mercury 217
Decomposition of hydrocarbons by expansion 219
Transference of heat by change of capacity in gas . . 221
Labarraque's disinfecting soda liquid 222
Anhydrous sulphate of soda . 230
Manufacture of optical glass 231
Peculiar class of optical deceptions 291
Sound during the conduction of heat 311
i Peculiar class of acoustical figures 314
Preparation of the lungs for holding the breath 358
Ventilation of lighthouse lamps 362
Thoughts on ray-vibrations 366
On ice and freezing water 372
On regelation , 377
Relations of gold and other metals to light 391
Conservation of force 443
Lecture on mental education 463
INDEX. . , 493
CHEMISTRY AND PHYSICS.
Analysis of Native Caustic Lime *.
ON THE NATIVE CAUSTIC LlME OF TUSCANY.
BY THE MARQUIS RIDOLFI.
THE interesting communication of Dr. Giovacchino Tacldei
respecting his discovery of caustic lime in the water of the
ancient bath of Santa Gonda, in August 1815, induced me to
visit the spot. The following is the result of my researches :
The bath is situated in a laguna in the corner of a field near
the high road to Pisa, which divides the plain called La Catena
from the mountains of Cigoli and San. Miniato. The soil is
a mixture of clay, calcareous earth, siliceous sand, and vege-
table matter. There are two sources of water; one issues
from the bottom of the laguna, and the other from the side.
The first is hot, raising the thermometer of Reaumur to 35|.
It is so saturated with lime, that upon cooling the water, it
* Quarterly Journal of Science, i. 260.
I reprint this paper at full length. It was the beginning of my communi-
cations to the public, and in its results very important to me. Sir Humphry
Davy gave me the analysis to make as a first attempt in chemistry at a time
when my fear was greater than my confidence, and both far greater than my
knowledge ; at a time also when I had no thought of ever writing an original
paper on science. The addition of his own comments and the publication of
the paper encouraged me to go on making, from time to time, other slight
communications, some of which appear in this volume. Their transference
from the ' Quarterly ' into other Journals increased my boldness ; and now that
forty years have elapsed and I can look back on what the successive com-
munications have led to, I still hope, much as their character has changed,
that I have not, either now or forty years ago, been too bold. M. F.
2 Analysis of native Caustic Lime. [1816.
deposits a considerable quantity. It contains also muriate of
lime and muriate of soda. The upper spring contains a little
carbonic acid gas, some sulphuretted hydrogen, and some
sulphate of soda. The following is the manner in which the
caustic lime is formed in this bath. The lower spring yields
a quantity of lime, but as this spring does not rise freely, but
oozes through the bottom of the bath, the lime forms a stra-
tum at the bottom of the lagune ; which stratum, absorbing
the carbonic acid gas of the water above, passes to the state of
a carbonate, and thus forms a defence to the lime, which is
continually depositing itself underneath, and prevents it losing
its causticity. In fact, the caustic lime is found enclosed
between the stratum of the carbonate of lime and the clayey
bottom of the laguna.
Signor Taddei found the masses of caustic lime so large,
that he could not get them out but by breaking them into
pieces. He, however, succeeded in removing the whole of it :
and I, having visited the spot two months after, found small
incrustations of the same substance newly formed.
ANALYSIS OF THE NATIVE CAUSTIC LIME. BY MR. FARADAY, ASSIST-
ANT IN THE LABORATORY OF THE ROYAL INSTITUTION.
THIS substance came to England in a bottle filled up with
water, the atmospherical air being perfectly excluded.
It is almost entirely soluble in muriatic acid without effer-
vescence, leaving nothing but a few light flocculi. The solu-
tion, when tested, was found to contain lime and iron.
A clean uniform piece of the substance was dried, as much
as could be, by bibulous paper. A fragment of it being heated
red, lost 62*26 per cent, of water.
The remainder of the original substance, weighing 188
grains, was dissolved in muriatic acid, and evaporated at a
high heat on the sand-bath, acid was again added, and the
evaporation repeated. Water was poured on it, and the silica
separated : when well washed, dried, and heated red, it
weighed 7*5 grains.
The filtered solution was precipitated by carbonate of pot-
ash, and the precipitate boiled in solution of pure potash.
The solution was separated from the solid matter, neutralized
by sulphuric acid, and precipitated by carbonate of ammonia.
1816.] Analysis of native Caustic Lime. 3
The precipitate, when well washed and dried, weighed 0*95
of a grain. It was soluble in sulphuric acid, and possessed
the properties of alumina.
Diluted sulphuric acid was added to the solid matter not
acted upon by the potash ; the whole boiled for some time,
and then filtered. The sulphate of lime obtained weighed,
after being heated red, 136 grains, which, estimating the lime
at 43 per cent., is equivalent to 58*48 grains of lime.
The sulphuric solution was precipitated by ammonia, and
two grains of oxide of iron were obtained.
Supposing the quantity of water in every part of the piece
first taken to be uniform, it would follow that the 188 grains
contained 117*05 of water; so that 70*95 was the quantity of
dry matter acted upon. The results were
Silica . . .
Lime . . .
Oxide of iron .
The loss is therefore rather more than two grains, which may,
perhaps, actually have taken place, and the difference may
have been derived from the unequal diffusion of water through-
out the piece.
Supposing 100 parts of the specimen to have been taken,
the analysis will stand thus :
Lime . . . 82-424
Silex . . . 10*570
Iron . . . 2-820
Alumina . . 1-.340
Loss . . . 2-846
It is perhaps worthy of observation, that during the solu-
tion of the substance in muriatic acid, a part only of the silica
separated; the greater part remained in solution until heat
was applied, when it gelatinized, as in the case where it is sepa-
rated by an acid and heat from its combination with alkali.
4 Analysis of native Caustic Lime. [1816.
OBSERVATIONS ON THE PRECEDING PAPER.
BY SiRH. DAVY, F.P.R.I., F.R.S.
THE Duchess of Montrose was so good as to send me the
caustic lime which is the subject of the preceding analysis ;
her Grace received it immediately from Tuscany, It was in a
hottle, carefully sealed and full of water. Some of the exterior
portions had become combined with carbonic acid before they
were collected, and from the colour, it appeared that there
were different portions of protoxide of iron in different parts
of the substance.
On examining the water, it was found to be a saturated
solution of lime, and it contained fixed alkali, but in quan-
tities so minute, that after the lime was separated, it could be
made evident only by coloured tests.
It appears from Mr. Faraday's analysis, that the menstruum
which deposits the solid substance must be a solution of silica
in lime-water, and heat is evidently the agent by which the
large quantity of lime deposited is made soluble and is enabled
to act on silica ; and the fact offers a new point of analogy
between the alkalies and the alkaline earths.
Vestiges of extinct volcanoes exist in all the low countries
on the western side of the Apennines ; and the number of
warm springs in the Tuscan, Roman, and Neapolitan States,
prove that a source of subterraneous heat is still in activity
beneath a great part of the surface in these districts.
Carbonic acid is disengaged in considerable quantities in
several of the springs at the foot of the Apennines ; and some
of the waters that deposit calcareous matter are saturated
solutions of this substance. Calcareous tufas of recent for-
mation are to be found in every part of Italy. The well-
known Travertine marble, Marmor Tiburtinum, is a pro-
duction of this kind ; and the Lago di Solfaterra near Tivoli,
of which I shall give a particular account on a future occasion,
annually deposits masses of this stone of several inches in
It is scarcely possible to avoid the conclusion, that the
carbonic acid, which by its geological agency has so modified
the surface of Italy, is disengaged in consequence of the
action of volcanic fires on the limestone, of which the Apen-
nines are principally composed, and liberated at their feet,
1817.] Escape of Gases through Capillary Tubes. 5
where the pressure is comparatively small; but the Tuscan
laguna offers the only instance in which the action of these
fires extends, or has extended, to the surface at which the
water collected in the mountains finds its way to the sea, so as
to enable it to dissolve caustic calcareous matter.
On the Escape of Gases through Capillary Tubes*.
As the mobility of a body, or the ease with which its particles
move among themselves, depends entirely upon its physical
properties, little delay would arise in the mind, on a consider-
ation of the probable comparative mobilities of the different
gases. These bodies being nearly similar in all the physical
properties, except specific gravity, which can interfere with
internal motions generated in them, would be supposed to
have those motions retarded in proportion as this latter cha-
racter increased ; but as this supposition has not been di-
stinctly verified, the following experiments, though possessed
of no peculiar claim to attention, may deserve to be recorded.
The apparatus was a copper vessel of the capacity of 100
cubic inches nearly, to which a condensing gauge was attached.
Four atmospheres of the gas to be tried were thrown into it,
and then a fine thermometer tube, 20 inches in length, was
fixed on by adjusting pieces : the gas was suffered to escape
until reduced to an atmosphere and a quarter, and the time
noticed by a seconds' pendulum. In this way,
Carbonic acid gas required 156*5 minutes to escape.
Olefiant gas 135'5
Carbonic oxide ,, 133 ,,
Common air ,, 128 ,, ,,
These experiments tend to show, that the mobility of the
gases tried decreases as their specific gravity increases, and
they are corroborated by others made with vanes. A wheel,
having small planes attached to it, as radii perpendicular to
the plane of motion, was made to rotate by a constant force in
atmospheres of different gases, and the times which the motion
* Quarterly Journal of Science, iii. 354.
6 Escape of Gases through Capillary Tubes. [1817.
continued, after the force was removed, diminished as the spe-
cific gravity increased ; as for instance, in
Carbonic acid it continued 6 seconds.
Common air 8 ,,
Coal-gas 10 ,,
Hydrogen gas 17
There is therefore every reason to believe, that the actual re-
lative mobilities of the gases are inversely as their specific
These experiments have been carried much further, in con-
sequence of some peculiar results obtained at low pressures ;
but as I have not been able to satisfy myself respecting the
causes, and have probably taken a wrong view of the pheno-
mena, I shall refrain from detailing them, and merely observe,
that there is no apparent connexion between the passage of
gases through small tubes and their densities at low pressures.
Olefiant gas then passes as readily as hydrogen, and twice as
rapidly as either carbonic oxide or common air, and carbonic
acid escapes far more readily than much lighter gases. Similar
results are also obtained by diminishing the bore of the tube,
and then even at considerable pressures, the effect produced
by mobility alone is interfered with by other causes, and dif-
ferent times are obtained. These anomalies depend, probably,
upon some peculiar loss or compensation of forces in the tube,
and offer interesting matter of discussion to mathematicians.
Experimental Observations on the Passage of Gases through
IN a previous communication I have noticed briefly some
curious effects which take place when gases are passed through
tubes at low pressures. They consist in an apparent inversion
of the velocities ; those which traverse quickest when the pres-
sure is high, moving more tardily as it is diminished, until they
are among those which require the longest time in passing the
tube; thus with equal high pressures equal volumes of hydro-
gen gas and olefiant gas passed through the same tube in the
following times :
* Quarterly Journal of Science, vii. 106.
1818.] Passage of Gases through Tubes. 7
Hydrogen in 57"
defiant gas in 135"-5;
but equal volumes of each passed through the same tube at
equal low pressures in the following times :
Hydrogen 8' 15"
defiant gas 8' 11".
Again, equal volumes of carbonic oxide and carbonic acid
gases passed at equal high pressures through the same tube,
occupied, the Carbonic oxide 133"
Carbonic acid 156"*5;
but at low pressures, Carbonic oxide 1 V 34"
Carbonic acid 9' 56".
I have lately had my attention again called to the subject,
but have not yet been able to satisfy myself of the cause of
this curious effect; nevertheless, as experiments do not always
owe their value to the hypothesis which accompanies them,
a few short observations on some made on this subject may be
The effect is always produced by fine tubes at low pressures,
but does not appear to belong to the mere obstruction by the
tube to the passage of the gas, nor have I been able to pro-
duce it without a tube. A very fine needle-hole was made in
a piece of platinum foil, and so arranged on a mercurial gaso-
meter, that the pressure of a small column of mercury sent
seven cubical inches of the following gases through in the
times mentioned, namely
Hydrogen 3''8 nearly, taking a mean,
Olefiant gas 9''2 ;
and when the pressure was increased, the same proportions in
the times was observed. Other similar experiments gave
Slits, cut in platinum foil by the edge of a penknife, did not
give so great a superiority to hydrogen as that mentioned
above, and the proportion varied with different slits ; still the
hydrogen passed most rapidly, and a difference of pressure
caused no difference in the relative times.
Three diaphragms were placed in different parts of the
same tube, each being perforated with a small hole, but the
effects produced in tubes were not observable here. Hydrogen
passed in 3*8 minutes, and olefiant gas in 9*1 minutes.
8 Passage of Gases through Tubes. [1818.
The gases were passed through discs of paper, and the num-
ber of discs was increased so as to increase the obstruction, the
pressure and quantity of gas remaining the same. With one disc
of drawing-paper 6'5 cubical inches of hydrogen passed in 7 ;
6'5 ,, ,, of olefiant gas in 18' ;
with two discs the hydrogen passed in 15H
,, olefiant gas ,, 38';
with three discs the hydrogen ,, 22''5
,, ,, olefiant gas ,, 57 f< 75.
Lastly, for the effect of obstruction, I used a tube filled with
pounded glass. This was uncertain, because on moving the
tube it was impossible, almost, not to move some of the par-
ticles within, and then, of course, circumstances were changed ;
but by sending the gases through one after the other, results
were obtained, the mean of which gave for hydrogen 3 ;< 4
,, ,, for olefiant gas 4 ;> 7.
It would seem from these experiments that mere obstruction
is not the cause of the effect observed in tubes, for when the
tubes are removed, and obstructions which retard much more
placed for them, the effect is lost ; and as the same aperture
produces no difference of effect at high or low pressures, the
variations between different apertures should probably be re-
ferred to some other cause.
I then endeavoured to ascertain some of the circumstances
attending on tubes. Both glass and metal tubes produce the
effect, and a metal tube, down which a wire had been thrust,
did not seem to have this influence on the passage of gases
through it altered. The effect is heightened as the gas is
made to pass more slowly through the tube ; and this, whether
the increased time be caused by diminished pressure, increased
length of tube, or diminished diameter. This may be well
illustrated by putting several very fine tubes together, for the
particular effect is thus increased whilst the time is shortened.
Two brass planes were ground together, and a few scratches
made down one of them so as to form very fine tubes 5 through
these olefiant gas passed in 26'*2, and hydrogen in 32 ;< 5.
Three glass tubes were taken of different diameter, and cut
into such lengths that they passed nearly equal quantities of
hydrogen gas in equal times by the same pressure ; their lengths
were 42, 10*5, and 1*6 inches. The longer tube passed the
1818.] Passage of Gases through Tubes. 9
hydrogen in ... 3 ; -7, the olefiant gas in '-75
the second in ... 3'*5 ,, 2''5
the smaller in ... 3''45 2'-8 ;
and in several other experiments there seemed to be nearly an
equal effect, when the quantity of gas passed in the same time
was the same.
I imagined that the specific gravity of the gases might have
some constant influence, but this does not seem to be the case;
carbonic oxide and olefiant gas are nearly of the same density ;
and if the effect depended upon their weight, it should be
nearly the same for both of them ; but this is not so ; seven
cubical inches of carbonic oxide required 4'6 minutes to
pass through a tube which was traversed by the same quantity
of olefiant gas under the same pressure in S'3 minutes, each
gas having been placed over caustic lime for some time pre-
viously ; and oxygen required to pass through the same tube
5 '45 minutes of time.
I placed three gauges in different parts of a tube, of such a
size that it passed olefiant and hydrogen gas in nearly equal
times ; the gauges were very obedient to the pressure of the
gas in the different parts of the tube, but I could not perceive
any difference between the effect of the different gases.
Such are some of the circumstances which affect and pro-
duce this curious effect : that the velocity of gases in passing
through tubes should be in some proportion to the pressure
on them is nothing particular ; but the singularity is, that the
ratio for the same gas varies with the pressure, and that this
variation differs in different gases ; thus the one which passes
with the greatest facility at low pressure, passes with the least
at high pressure.
It may be deduced from the experiments at high pressures
and on obstructions, that the fluidity of the gas has little or
nothing to do in this case, for where it alone can have an in-
fluence, the indications are the same at all pressures, and the
gas of least density passes in the shortest time ; thus com-
paring hydrogen with olefiant gas, and considering its time 1,
the time of the latter will be in the experiments already men-
tioned, as 2-38, 2-42, 2-4, 2'57, 2'46, 2'57 ratios, which do not
differ much from each other, though the times, pressure, ob-
structions, and quantities of gas used vary very considerably.
10 Passage of Gases through Tubes. [1818.
Neither is the variation among the different gases between
the ratio of the velocity and pressure, connected with specific
gravity, at least I have not been able to observe such a con-
nexion. I have quoted an experiment, ot rather the general
result of several, on carbonic oxide and olefiant gases, and it is
adverse to the supposition ; and in others, made on sulphurous
acid gas and ammoniacal gas, still further departures from the
order of the densities were observed.
If a tube sufficiently fine and long be connected with a por-
tion of gas under high pressure, so that the time occupied in
its passage through it be considerable, the effect will be pro-
duced, i. e. the times of different gases will vary from each
other, but not according to their specific gravities ; if the tube,
however, be cut off so that the gases pass quickly, then the
times will be as the specific gravity. Now, in the long tube, the
pressure and velocity will vary throughout its length, the pres-
sure being greatest at the internal or connected end, and least
at the other extremity, whilst the velocity is least at the end
towards the reservoir, and greatest at the other. But the
ratio by which the pressure and velocity decrease and increase,
appears different for and peculiar to each gas. At the end of
the long tube the olefiant gas issues more rapidly than hydro-
gen, though the pressure at the reservoir is the same; but
shorten the tube, and let that part in which high pressures only
exist confine the gases in their passage, and the hydrogen gas
will surpass the olefiant gas in velocity as far as 4 or 5 does 2.