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act on silver, yet that is not the case ; pure muriatic acid dissolves a small
portion of silver very readily.



74 On the Alloys of Steel [1822.

of rhodium was formed, distinguishable by its colour, and by
the triple salt it formed with muriate of soda.

To analyse the compound of steel with iridium and osmium,
the alloy should be acted on by dilute sulphuric acid, and the
residuum boiled in the acid ; the powder left is to be collected
and heated with caustic soda in a silver crucible to dull redness
for a quarter of an hour, the whole to be mixed with water,
and having had excess of sulphuric acid added, it is to be di-
stilled, and that which passes over condensed in a flask : it will
be a solution of oxide of osmium, will have the peculiar smell
belonging to that substance, and will give a blue precipitate
with tincture of galls. The portion in the retort being then
poured out, the insoluble part is to be washed in repeated
portions of water, and then being first slightly acted on by
muriatic acid to remove the iron, is to be treated with nitro-
muriatic acid, which will give a muriate of iridium.

In these analyses, an experienced eye will frequently per-
ceive, on the first action of the acid, the presence of the
alloying metal, When this is platinum, gold, or silver, a film
of the metal is quickly formed on the surface of the acid.

Of alloys of platinum, palladium, rhodium, and iridium and
osmium, a ready test is offered when the point is not to ascer-
tain what the metal is, but merely whether it be present or not.
For this purpose we have only to compare the action of the
same acid on the alloy and on a piece of steel; the increased
action on the alloy immediately indicates the presence of the
metal ; and by the difference of action, which on experience
is found to be produced with the different metals, a judgement
may be formed even of the particular one present.

The order in which the different alloys stand with regard
to this action is as follows : steel, chromium alloy, silver alloy,
gold alloy, nickel alloy, rhodium alloy, iridium and osmium
alloy, palladium alloy, platinum alloy. With similar acid the
action on the pure steel was scarcely perceptible ; the silver
alloy gave very little gas, nor was the gold much acted on.
All the others gave gas copiously, but the platinum alloy in
most abundance.

In connexion with the analysis of these alloys, there are
some very interesting facts to be observed during the action
of acids on them, and perhaps none of these are more striking



1 822.] On the Alloys of Steel. 75

than those last referred to. When the alloys are immersed
in diluted acid, the peculiar properties which some of them
exhibit, not only mark and distinguish them from common
steel, and from each other, but also give rise to some consider-
ations on the state of particles of matter of different kinds
when in intimate mixture or in combination, which may lead
to clearer and more perfect ideas on this subject.

If two pieces, one of steel, and one of steel alloyed with pla-
tinum, be immersed in weak sulphuric acid, the alloy will be
immediately acted on with great rapidity and the evolution of
much gas, and will shortly be dissolved, whilst the steel will
be scarcely at all affected. In this case it is hardly possible
to compare the strength of the two actions. If the gas be col-
lected from the alloy and from the steel for equal intervals of
time, the first portions will surpass the second some hundreds
of times.

A very small quantity of platinum alloyed with steel confers
this property on it : -yfa increased the action considerably ; with
-gl-Q and T n it was powerful ; with 10 per cent, of platinum it
acted, but not with much power ; with 50 per cent, the action
was not more than with steel alone ; and an alloy of 90 platinum
with 20 steel was not affected by the acid.

The action of other acids on these alloys is similar to that
of sulphuric acid, and is such as would be anticipated : dilute
muriatic acid, phosphoric acid, and even oxalic acid, acted on
the platinum alloy with the liberation of more gas than from
zinc ; and tartaric acid and acetic acid rapidly dissolved it.
In this way chalybeate solutions, containing small portions of
protoxide of iron, may be readily obtained.

The cause of the increased action of acids on this and
similar alloys, is, as the President of this Society suggested to
us, probably electrical. It may be considered as occasioned
by the alloying metal existing in such a state in the mass, that
its particles form voltaic combinations with the particles of
steel, either directly or by producing a definite alloy, which is
diffused through the rest of the steel ; in which case the
whole mass would be a series of such voltaic combinations : or
it may be occasioned by the liberation, on the first action of
the acid, of particles, which, if not pure platinum, contain, as
has been shown, a very large proportion of that metal, and



76 On the Alloys of Steel. [1822.

which, being in close contact with the rest of the mass, form
voltaic combinations with it in a very active state : or, in the
third place, it may result from the iron being mechanically
divided by the platinum, so that its particles are more readily
attacked by the acid, analogous to the case of protosulphuret
of iron.

Although we have not been able to prove by such experi-
ments, as may be considered strictly decisive, to which of these
causes the action is owing, or how much is due to any of them,
yet we do not hesitate to consider the second as almost en-
tirely, if not quite, the one that is active. The reasons which
induce us to suppose this to be the true cause of the action,
rather than any peculiar and previous arrangement of the par-
ticles of steel and platinum, or than the state of division of the
steel, are, that the two metals combine in every proportion we
have tried, and do not in any case exhibit evidences of a
separation between them, like those, for instance, which steel
and silver exhibit ; that when, instead of an acid, weaker
agents are used, the alloy does not seem to act with them as if
it were a series of infinitely minute voltaic combinations of steel
and platinum, but exactly as steel alone would do ; that the mass
does not render platinum wire more negative than steel, as it
probably in the third case would do ; that it does not rust
more rapidly in a damp atmosphere ; and that when placed in
saline solutions, as muriate of soda, &c., there is no action
takes place between them. In such cases it acts just like
steel ; and no agent that we have as yet tried, has produced
voltaic action that was not first able to set a portion of the
platinum free by dissolving out the iron.

Other interesting phenomena exhibited by the action of acid
on these steels, are the differences produced when they are
hard and when soft. Mr. Daniel, in his interesting paper on
the mechanical structure of iron, published in the Journal of
Science, has remarked, that pieces of hard and soft steel being
placed in muriatic acid, the first required fivefold the time of
the latter to saturate the acid ; and that when its surface was
examined, it was covered with small cavities like worm-eaten
wood, and was compact and not at all striated, and that the
latter presented a fibrous and wavy texture.

The properties of the platinum alloy have enabled us to



1 822.] On the Alloys of Steel 77

observe other differences between hard and soft steel equally
striking. When two portions of the platinum alloy, one hard
and one soft, are put into the same diluted sulphuric acid and
suffered to remain for a few hours, then taken out and ex-
amined, the hard piece presents a covering of a metallic black
carbonaceous powder, and the surface is generally slightly
fibrous ; but the soft piece, on examination, is found to be
covered with a thick coat of grey metallic plumbaginous matter,
soft to the touch, and which may be cut with a knife, and its
quantity seven or eight times that of the powder on the hard
piece : it does not appear as if it contained any free charcoal,
but considerably resembles the plumbaginous powder Mr.
Daniel describes as obtained by the action of acid on cast iron.

The same difference is observed if pure steel be used, but
it is not so striking ; because, being much less rapidly attacked
by the acid, it has to remain longer in it, and the powder pro-
duced is still further acted on.

The powder procured from the soft steel or alloy in these
experiments, when it has not remained long in the acid, ex-
actly resembles finely divided plumbago, and appears to be a
carburet of iron, and probably of the alloying metal also. It
is not acted on by water, but in the air the iron oxidates and
discolours the substance. When it remains long in the acid,
or is boiled in it, it is reduced to the same state as the powder
from the hard steel or alloy.

When any of these residua are boiled in diluted sulphuric
or muriatic acid, protoxide of iron is dissolved, and a black
powder remains unalterable by the further action of the acid ;
it is apparently in greater quantity from the alloys than from
pure steel, and when washed, dried, and heated to 300 or 400
in the air, burns like pyrophorus, with much fume: or if lighted,
burns like bitumen, and with a bright flame ; the residuum is
protoxide of iron, and the alloying metal. Hence, during the
action of the acid on the steel, a portion of hydrogen enters
into combination with part of the metal and the charcoal, and
forms an inflammable compound not acted upon by the acid.

Some striking effects are produced by the action of nitric
acid on these powders. If that from pure steel be taken, it is
entirely dissolved ; and such is also the case if the powder be
taken from an alloy the metal of which is soluble in nitric acid ;



78 On the Alloys of Steel. [1822.

but if the powder is from an alloy the metal of which is not
soluble in nitric acid, then a black residuum is left not touched
by the acid ; and which, when washed and carefully dried, is
found, when heated, to be deflagrating ; and with some of the
metals, when carefully prepared, strongly explosive.

The fulminating preparation obtained from the platinum alloy,
when dissolved in nitromuriatic acid, gave a solution contain-
ing much platinum and very little iron. When a little of it was
wrapped in foil and heated, it exploded with much force, tear-
ing open the foil, and evolving a faint light. When dropped
on the surface of heated mercury, it exploded readily at 400
of Fahrenheit, but with difficulty at 370. When its tempera-
ture was raised slowly, it did not explode, but was decomposed
quietly. When detonated in the bottom of a hot glass tube,
much water and fume were given off, and the residuum col-
lected was metallic platinum with a very little iron and charcoal.
We are uncertain how far this preparation resembles the ful-
minating platinum of Mr. Edmund Davy.

In these alloys of steel the differences of specific gravity are
not great, and may probably be in part referred to the denser
state of the metals from more or less hammering : at the same
time it may be observed, that they are nearly in the order of
the specific gravities of the respective alloying metals.

The alloys of steel with gold, tin, copper, and chromium,
we have not attempted in the large way. In the laboratory,
steel and gold were combined in various proportions ; none
of the results were so promising as the alloys already named,
nor did either tin or copper, as far as we could judge, at all
improve steel. With titanium we failed, owing to the imper-
fection of crucibles. In one instance, in which the fused but-
ton gave a fine damask surface, we were disposed to attribute
the appearance to the presence of titanium ; but in this we
were mistaken ; the fact was, we had unintentionally made
wootz. The button, by analysis, gave a little silex and alumina,
but not an atom of titanium ; menachanite, in a particular state
of preparation, was used : this might possibly contain the
earths or their basis, or they may have formed a part of the
crucible.

M. Berthier, who first made the alloy of steel and chromium*,
* Annales de Chimie, xvii, 55.



1 822.] On the Alloys of Steel. 79

speaks very favourably of it. We have made only two experi-
ments. 1600 grains of steel, with 16 of pure chrome, were
packed into one of the best crucibles, and placed in an excel-
lent blast furnace : the metals were fused, and kept in that
state for some time. The fused button proved good and forged
well : although hard, it showed no disposition to crack. The
surface being brightened, and slightly acted on by dilute sul-
phuric acid, exhibited a crystalline appearance; the crystals,
being elongated by forging, and the surface again polished,
gave, by dilute acid, a very beautiful damask. Again, 1600
grains of steel with 48 of pure chrome were fused: this gave a
button considerably harder than the former. This too was as
malleable as pure iron, and also gave a very fine damask. Here
a rather curious phenomenon was observed : the damask was
removed by polishing, and restored by heat without the use of
any acid. The damasked surface, now coloured by oxidation,
had a very novel appearance : the beauty was heightened by
heating the metal in a way to exhibit all the colours caused by
oxidation, from pale straw to blue, or from about 430 to 600
of Fahrenheit. The blade of a sabre, or some such instrument
made from this alloy, and treated in this way, would assuredly
be beautiful, whatever its other properties might be; for of
the value of the chrome alloy for edge-tools we are not pre-
pared to speak, not having made trial of its cutting powers.
The sabre blade, thus coloured, would amount to a proof of its
being well tempered ; the blue back would indicate the temper
of a watch-spring, while the straw colour towards the edge
would announce the requisite degree of hardness. It is con-
fessed, that the operation of tempering any blade of consider-
able length in this way would be attended with some difficulty.
In the account now given of the different alloys, only one
triple compound is noticed, namely, steel, iridium and osmium ;
but this part of the subject certainly merits further investiga-
tion, offering a wide and interesting field of research. Some
attempts to form other combinations of this description proved
encouraging, but we were prevented, at the time, by various
other avocations, from bestowing on them that attention and
labour they seemed so well to deserve*.

* It is our intention to continue these experiments at every opportunity ;
but they are laborious, and require much time and patience.



80 On the Alloys of Steel [1822.

It is a curious fact, that when pure iron is substituted for
steel, the alloys so formed are much less subject to oxidation.
3 per cent, of iridium and osmium, fused with some pure iron,
gave a button, which, when forged and polished, was exposed,
with many other pieces of iron, steel, and alloys, to a moist
atmosphere : it was the last of all showing any rust. The
colour of this compound was distinctly blue ; it had the pro-
perty of becoming harder when heated to redness, and
quenched in a cold fluid. On observing this steel-like cha-
racter, we suspected the presence of carbon : none, however,
was found, although carefully looked for. It is not improbable
that there may be other bodies, besides charcoal, capable of
giving to iron the properties of steel ; and though we cannot
agree with M. Boussingault*, when he would replace carbon
in steel by silica or its base, we think his experiments very in-
teresting on this point, which is worthy further examination.

We are not informed as to what extent these alloys, or any of
them, have been made at home, or to what uses they have been
applied ; their more general introduction in the manufacture of
cutlery would assuredly add to the value, and consequently to
the extension of that branch of trade. There are various other
important uses to which the alloys of steel may advantageously
be applied. If our information be correct, the alloy of silver,
as well as that of platinum, has been to some considerable extent
in use at His Majesty's Mint. We do know, that several of
the alloys have been diligently and successfully made on the
Continent, very good specimens of some of them having been
handed to us ; and we are proud of these testimonies of the
utility of our endeavours.

To succeed in making and extending the application of these
new compounds, a considerable degree of faithful and diligent
attention will be required on the part of the operators. The
purity of the metals intended to form the compound is essen-
tial ; the perfect and complete fusion of both must in every
case be ascertained : it is further requisite that the metals be
kept for some considerable time in the state of thin fusion :
after casting, the forging is to be attended to with equal care ;
the metal must on no account be overheated ; and this is more
particularly to be attended to when the alloying metal is fusible
* Annales de Chimie, xvi. 10.



1 823. ] On Hydrate of Chlorine. 8 1

at a low temperature, as silver. The same care is to be ob-
served in hardening : the article is to be brought to a cherry-red
colour, and then instantly quenched in the cold fluid.

In tempering, which is best performed in a metallic bath
properly constructed, the bath will .require to be heated for the
respective alloys, from about 70 to 100 of Fahrenheit above
the point of temperature required for the best cast steel. We
would further recommend, that this act of tempering be per-
formed twice ; that is, at the usual time before grinding, and
again just before the last polish is given to the blade. This
second tempering may perhaps appear superfluous, but upon
trial its utility will be readily admitted. We were led to adopt
the practice by analogy, when considering the process of
making and tempering watch-springs.



On Hydriodide of Carbon *.

IN the ' Philosophical Transactions 'for 1821, 1 have described
a compound of chlorine and olefiant gas f, but had not at that
time the means of ascertaining its composition. Since then I
have obtained it in greater quantity, and analysed it. Four
grains were passed in vapour over heated copper, in a green
glass tube ; iodide of copper was formed, and pure olefiant
gas evolved, which amounted to 1*37 cubic inch. As 100 cubic
inches of olefiant gas weigh about 30' 15 grs., so 1'37 cubic
inch will weigh 0'4<13 gr. Now 4 grains minus 0*413 leaves 3*587
iodine, and 3-587 : 0-413 : : 117-75 : 13-55 nearly. Now 13*55
is so nearly the number of two proportions of olefiant gas, that
the substance may be considered as composed of

1 proportion of Iodine .... 1 1 7*75

2 proportions of Olefiant gas . . 13*4

and is therefore analogous in its constitution to the compound
of chlorine and olefiant gas, sometimes called chloric ether.



On Hydrate of Chlorine J.

IT was generally considered before the year 1810, that chlo-
rine gas was condensible by cold into a solid state ; and we

* Quarterly Journal of Science, xiii. 429. f See page 61.

% Quarterly Journal of Science, xv, 71



82 On Hydrate of Chlorine. [1823.

were first instructed by Sir Humphry Davy, in his admirable
researches into the nature of that substance, published in the
' Philosophical Transactions' for 1810-11, that the solid body,
obtained by cooling chlorine gas, was a compound with water ;
and that the dry gas could not be condensed at a temperature
equal even to 40 Fahr., whilst on the contrary, moist gas,
or a solution of chlorine in water, crystallized at the tempera-
ture of 40 Fahr.

M. Thenard, in his ' Traite de Chimie,' has described the
deposition of the hydrate of chlorine by cold from an aqueous
solution of the gas. It forms crystals of a bright yellow colour,
which liquefy when their temperature is slightly raised, and in
so doing give off abundance of gas.

This substance may be obtained well crystallized, by intro-
ducing into a clean bottle of the gas, a little water, but not
sufficient to convert the whole into hydrate, and then placing
the bottle in a situation the temperature of which is about or
below freezing, for a few days : and I have constantly found
the crystals better formed in the dark than in the light.
The hydrate is produced in a crust or in dendritical crystals;
but being left to itself, will in a few days sublime from one
part of the bottle to another in the manner of camphor, and
form brilliant and comparatively large crystals. These are of
a bright yellow colour, and sometimes, though rarely, are
delicate prismatic needles extending from half an inch to two
inches into the atmosphere of the bottle : generally they are
of shorter forms, and when most perfect and simple, have
appeared to me to be acute flattened octahedra, the three axes
of the octahedron having different dimensions.

Though a solution of chlorine deposits the hydrate when
cooled, yet a portion remains in solution, and the crystals also
dissolve slowly in water. It is therefore soluble, though not
so much so as chlorine gas. When a solution of chlorine is
cooled gradually till the whole is frozen, there is a perfect
separation of the hydrate of chlorine from the rest of the
water, or rather from the ice ; for crystals of ice, formed
in a solution of chlorine, when washed in pure water, and then
dissolved, do not trouble nitrate of silver.

I neglected to ascertain the specific gravity of the crystals
whilst the weather was cold and they were readily obtainable ;



1823.] On Hydrate of Chlorine. 83

but I have endeavoured since to do so by means of cooling
mixtures. The hydrate in thin plates was put into solutions
of muriate of lime of different densities, but of the temperature
of 32 Fahr. It seemed to remain in any part of a solution of
specific gravity 1*2, but there was constantly a slight liberation
of gas ; and as minute and imperceptible bubbles may have
adhered to the hydrate, the result can only be considered as
a loose approximation. The solid crystals would probably be
heavier than 1*2.

The hydrate of chlorine acts upon substances, as might be
expected, from the action of chlorine upon the same substances,
and it may perhaps now and then offer a convenient form for
its application in experiment. When put into alcohol, an
elevation of temperature amounting to 8 or 10 took place.
There was rapid action, much ether, and muriatic acid formed,
and a small portion of a triple compound of chlorine, carbon
and hydrogen.

When put into solutions of ammoniacal salts it liberated
nitrogen gas, formed muriatic acid, and also chloride of nitro-
gen, which remained undissolved at the bottom of the solution.

In aqueous solution of ammonia similar effects were pro-
duced, but less chloride of nitrogen was formed.

In order to arrive at a knowledge of the composition of this
substance, I adopted the following process : The crystals were
collected together by a small quantity of solution of chlorine,
then filtered and pressed between successive portions of bibu-
lous paper at a temperature of 32 (care being taken to ex-
pose them as little as possible to the air), until as dry as
they could be rendered by this means. A glass flask with a
narrow neck, arid containing a portion of water at 32, having
been previously counterpoised, a portion of the crystals were
immediately after the last pressing introduced into it ; they
sank to the bottom of the water, and the flask being again
weighed, the quantity of crystals introduced was ascertained.
A weak solution of pure ammonia was then poured into the
water in the flask, care being taken to add considerable excess
over that required by the chlorine beneath. The whole was
left for twenty-four hours, in which time the chlorine had had
sufficient opportunity to act on the ammonia, and any portion
of chloride of nitrogen that might at first have been formed
would be resolved into its elements, and its chlorine be con-



84 On Hydrate of Chlorine. [1823.

verted into muriatic acid. It was then slightly heated, neu-
tralized by pure nitric acid, precipitated by nitrate of silver,
and the chloride of silver obtained and weighed.

The following is an experiment conducted in this way :
65 grains of the pressed crystals were put into the flask, and
the ammonia added ; at one time there was a faint smell of
chloride of nitrogen for an instant at the mouth of the flask,
and a little more ammonia was added. The next day 73'2 grs.



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