_Oxy-muriate of Mercury._
_Corrosive Muriate of Mercury._ _Corrosive Sublimate._
QUALITIES. _Form_, a crystalline mass, composed of very small prismatic
crystals, which is easily pulverized, and undergoes a slight alteration
by exposure to air, becoming on its surface opaque and pulverulent.
Light, however, has no effect upon it, although a different opinion has
existed, and it has accordingly been recommended to be kept in black
bottles. _Odour_, none. _Taste_, very acrid, with a metallic
astringency, occasioning a sensation of obstruction in the throat which
continues for some time. _Sp. gr._ 5·1398. When pulverised and thrown
upon burning coals, it is immediately volatilized, giving out a thick
white smoke of a very pungent smell, which irritates the mucous
membranes extremely, and is highly dangerous to those who inhale it.
CHEMICAL COMPOSITION. According to the latest views, it is a
_Bi-chloride_ of mercury, consisting of one proportional of mercury, to
two proportionals of chlorine. In the French codex, it is termed
“_Deuto-Chloruretum Hydrargyri_.” SOLUBILITY. It is soluble in eleven
parts of cold, and in three of boiling water, and in half its weight of
alcohol; it is also very soluble in æther; indeed this latter liquid has
the curious property of abstracting it from its solution in water, when
agitated with it. Its solubility in water is greatly increased by the
addition of a few drops of rectified spirit, or of muriatic acid. In a
solution of muriate of ammonia it is seventeen times more soluble than
in water, no decomposition however arises; it is therefore probable that
a triple salt is formed; it is also soluble in the sulphuric, nitric,
and muriatic acids, and may be obtained again unaltered, by simply
evaporating the solutions. Dr. Davy, in his late researches upon
corrosive sublimate states that with muriatic acid, common salt, and
some other muriates, it forms definite compounds remarkable for their
solubility. Its watery solution is said to change vegetable blues to
green, but this is an optical fallacy, (_see page 306_.) On exposure to
light this solution slowly undergoes decomposition; but Dr. Davy has
shewn that corrosive sublimate remains unaltered when exposed in
solution in media having a strong affinity for it, as in alcohol, æther,
muriatic acid, &c. and that decomposition only takes place under
circumstances of complicated affinities, as in the instance of _Liquor
Hydrargyri Oxymuriatis_, and in that of the aqueous solution; in which
cases Calomel and Muriatic acid appear to be formed, and oxygen to be
evolved. INCOMPATIBLE SUBSTANCES. The _carbonates of the fixed_ alkalies
precipitate it of a yellow hue, but the precipitates are not pure
oxides; _ammonia_ forms with it a white triple compound. _Lime water_
decomposes it more perfectly than any alkaline body, occasioning a
precipitate of a deep yellow colour,[524] which is a per-oxyd of mercury
containing a little muriatic acid; this result forms a useful lotion to
ill conditioned ulcers, and has been long known under the title of _Aqua
Phagadenica_; f℥j of lime water should be employed for the decomposition
of two grains of the salt. _Tartarized antimony_, _nitrate of silver_,
_acetate of lead_, _sulphur_, _sulphuret of potass_, and _soaps_,
decompose it. _Iron_, _lead_, _copper_, _bismuth_, and _zinc_, in their
metallic state, also decompose it, producing precipitates which consist
of an amalgam of the metal employed, except in those cases where the
metal in question refuses to amalgamate with mercury, when this latter
metal appears as a metallic dew, composed of very minute globules, with
calomel; hence mortars of glass or earthenware should be used for
dispensing this article; when triturated with olive oil, the oil becomes
white, and when boiled with it, _calomel_ is precipitated; the same
happens if sugar be substituted for oil. The volatile oils reduce it.
When Oil of Turpentine was used, some traces of artificial camphor was
discovered by Dr. Davy, and when the oils of Cloves and Peppermint, a
purple compound distilled over, consisting of the oil employed and
muriatic acid. The following vegetable infusions produce precipitates,
viz. _the infusions and decoctions of chamomile_, _horse-radish root_,
_calumba root_, _catechu_, _cinchona_, _rhubarb_, _senna_, _simarouba_,
_oak bark_, _tea_ and _almond emulsion_. Swediaur observes, that “many
authors have recommended _sublimate_ combined with bark, but that a
reciprocal decomposition is thus produced, by which the energies of both
remedies are alike annulled;” to this ignorance, however, he thinks that
many patients have been indebted for their lives; for, says he, “I see
every day examples of weak and very delicate persons of both sexes, to
whom ignorant practitioners prescribe, and sometimes in very large
doses, the _corrosive sublimate_, with a decoction of bark; certainly
without curing the syphilis, but at the same time without occasioning
those grave and dangerous symptoms, which that acrid medicine would
certainly produce, if given alone, or without that decoction.” We have
here presented the reader with the opinion of Swediaur; but it is just
to state, that the experience of this country has rather tended to
subvert, than to confirm, such a belief. That the corrosive sublimate of
mercury is actually decomposed by the vegetable principles of the bark
is sufficiently evident, but it would seem that the oxide thus
developed, and recombined with vegetable extractive, is a very active
mercurial, especially with respect to its alterative powers. The same
observation will, to a certain extent, apply to the results of its
decomposition by other agents; the fixed alkalies have been found by
actual experiment to be incapable of disarming this salt of its
virulence, because, as Orfila has stated, the oxide liberated is, in
itself, an active poison. Mr. Rose has lately transmitted to me a
formula for the preparation of “_Alterative Drops_,” which he states,
from ample experience, to possess very considerable powers as a
mercurial, and to excite ptyalism, with a quickness and certainty which
characterize but few preparations of the same class. The principal
ingredients are an alcoholic solution of _corrosive sublimate_ and a
vinous solution of tartarized antimony. It is scarcely necessary to
observe that upon admixture a mutual decomposition takes place; the
_peroxide of mercury_ is precipitated by the alkaline element of the
antimonial compound, whilst this latter salt, having its affinities thus
overthrown, parts with the _protoxide of antimony_; so that the
preparation holds a considerable quantity of insoluble matter in
suspension, and which is to be carefully incorporated with the liquid by
shaking the phial, whenever the drops are administered. Now there can be
but little doubt but that the activity of this preparation is owing to
the _peroxide of mercury_, thus diffused in a state of minute division,
while at the same time the antimonial protoxide very probably disposes
the stomach and system to be more readily influenced by it, for reasons
which have been fully discussed in the first part of this work, p. 152.
MED. USES. It is one of the most acrid and active of all metallic
preparations; in well directed doses, however, it is frequently of
service in secondary syphilis, and in cases of anomalous disease, when
it would be improper to administer the other forms of mercury.[525] In
obstinate cutaneous diseases its administration in small doses is often
very serviceable; I have, however, seen extreme emaciation and hectic
fever produced by its too long continued exhibition, although ptyalism
was never occasioned. Its application also as a lotion to leprous
affections, in the proportion of about one grain to a fluid-ounce and a
half of some liquid vehicle, I have frequently seen highly beneficial;
in directing the use of so acrid a lotion, we should caution the patient
not to touch his eyes until his hands have been washed; in consequence
of a neglect of this kind I have seen a very severe ophthalmia produced.
The practitioner should also remember that the system may become
affected by such external applications; a case stands recorded in which
a girl of five years old became salivated, and died, in consequence of
an application made to the head for the cure of _Tinea_, which consisted
of Pomatum rubbed up with a few grains of this salt. Its internal
exhibition should be accompanied with mucilaginous drinks; when an
overdose has been taken, the _white_ of egg, diluted with water, is the
best antidote, for Orfila has found that albumen decomposes it, reducing
it to the state of mild muriate, whilst the compound which it forms with
it is inert. Many examples are recorded of the success of this practice.
In the Transactions of the King and Queen’s College of Physicians in
Ireland, an interesting case of this kind is related by Dr. Lendrick; it
is, however, at the same time but justice to state, that there are
instances also of the failure of this antidote. In the 41st volume of
the _London Medical and Physical Journal_, p. 204, the reader will find
the case of a girl, who was poisoned by a drachm of Sublimate, and who,
notwithstanding the copious ingestion of albumen, died in ninety hours.
More recently vegetable gluten, as existing in wheat-flower, is said to
answer as well as albumen; for the administration of which all that is
required is to give wheat-flower and water. Dose, gr. 1/8 to ½, see
_Liquor Hydrargyri Oxymuriatis_, and _Form. 142_. ADULTERATIONS. It
ought to be volatilized by heat; it is frequently met with in commerce
contaminated with muriate of iron, sometimes with arsenic; the presence
of calomel is at once discovered from its insolubility. TESTS OF ITS
PRESENCE. If any powder be suspected to contain this salt, expose it to
heat in a coated tube, as directed in the treatment of arsenic, but
without any carbonaceous admixture, when corrosive sublimate, if
present, will rise and line the interior surface with a shining white
crust. This crust is then to be dissolved in distilled water, and
assayed by the following tests; 1st, _lime water_ will produce, if the
suspected solution contains this salt, a precipitate of an orange yellow
colour. 2d, a single drop of a dilute solution of _sub-carbonate of
potass_ will at first produce a white precipitate, but on a still
farther addition of the test, an orange-coloured sediment will be
formed. 3rd, _sulphuretted water_ will throw down a dark coloured
precipitate, which when dried and strongly heated may be volatilized
without any alliaceous odour. 4th, _ammonia_ produces a white
precipitate, which is an insoluble triple salt, composed of muriatic
acid, ammonia, and oxide of mercury, which, on being heated, grows
yellow; it passes afterwards to a red, and gives out ammoniacal gas,
nitrogen, calomel, and metallic mercury. In this operation the oxide is
supposed to be decomposed by the hydrogen which results from a portion
of the ammonia. 5th, _Nitrate of tin_, according to Dr. Bostock, is
capable of detecting the three-millionth part of a grain; a single drop
will occasion an immediate and copious dark-brown precipitate. All the
above precipitates, if rubbed on a bright plate of copper, will render
its surface very white. Where the salt is mixed with various coloured
liquids, we must proceed as directed under the head of Arsenic. A very
ingenious application of galvanic electricity has been also proposed by
Mr. Silvester, for the detection of _corrosive sublimate_, which will
exhibit the mercury in a metallic state. A piece of zinc or iron wire
about three inches in length, is to be twice bent at right angles, so as
to resemble the Greek letter Π, the two legs of this figure should be
distant about the diameter of a common gold wedding ring from each
other, and the two ends of the bent wire must afterwards be tied to a
ring of this description. Let a plate of glass, not less than three
inches square, be laid as nearly horizontal as possible, and on one side
drop some sulphuric acid, diluted with about six times its weight of
water, till it spreads to the size of a halfpenny. At a little distance
from this, towards the other side, next drop some of the solution
supposed to contain corrosive sublimate, till the edges of the two
liquids become joined; and let the wire and ring, prepared as above, be
laid in such a way that the wire may touch the acid, while the gold ring
is in contact with the suspected liquid. If the minutest quantity of
corrosive sublimate be present, the ring in a few minutes will be
covered with mercury on the part which touched the fluid. This
experiment may be beautifully simplified in the following manner; drop a
small quantity of solution containing corrosive sublimate on a piece of
gold, and bring into contact a key, or some piece of iron, so as to form
a galvanic circuit, when the gold will be immediately whitened. A
solution of nitrate of silver will, under similar circumstances,
occasion on the gold a white precipitate, but as no amalgamation takes
place, it is readily wiped off, and cannot possibly occasion any
fallacy.[526]
Certain metals likewise decompose solutions of this salt, by virtue of
superior affinity; in those cases where the precipitating metal is
capable of forming a direct union with Mercury, we shall find the
precipitates to consist of an amalgam of the metal employed; where no
such combination takes place, the mercury will be frequently seen
standing on the surface as a metallic dew. This is particularly striking
where iron or steel has been employed; these metals are also at the same
time blackened by it.
Brugnatelli[527] has proposed the following method of distinguishing
_corrosive sublimate_ from _arsenic_—Take a quantity of fresh wheat
starch, mix with water, and add a sufficient quantity of _iodine_ to
give the liquid a blue colour; if _corrosive sublimate_ or _arsenic_ be
added to this liquor, the colour is alike destroyed and it becomes
reddish, but if the change has been effected by the latter substance, a
few drops of sulphuric acid will restore the blue colour, but if by the
former it is not recoverable by such means.[528]