MERCURY AND ITS COMPOUNDS.
Of the preparations of mercury, corrosive sublimate is the most
important to the toxicologist; for although they all possess in a
greater or less degree poisonous properties, yet the instances in which
the other compounds have been used to destroy life are extremely rare.
The treatment in all cases must be the same. It is worthy of remark that
mercury, whilst in the metallic state, is destitute of injurious
properties, but if oxidized or otherwise rendered fit for absorption, it
may give rise to dangerous symptoms. Thus, workers in mercurial mines
suffer much, as did those who were employed in silvering looking-glasses
by the old process. Large doses (from half a pound to two pounds) have
been given in obstinate cases of constipation, intussusception, &c.,
without any remarkable effect.
CORROSIVE SUBLIMATE (_Oxymuriate of Mercury_, _Chloride of Mercury_,
_Bichloride of Mercury_).--This preparation of Mercury, which, more
strictly speaking, belongs, like the chlorides of zinc and antimony, to
the class Corrosives, is usually met with in the form of imperfect
crystalline masses, or as a white powder. It has an acrid, coppery
taste, so powerful that but little could be swallowed without the
individual becoming aware of it. It is very soluble in water. Three
grains is the smallest quantity that has been known to prove fatal; and
from this to five grains may probably be stated as the average dose
necessary to destroy life. Recovery has taken place after as much as
eighty grains had been swallowed. Death has occurred in less than half
an hour; while, in some instances, life has been maintained until the
sixth day, and in one instance (where between three and four scruples
had been swallowed) until the twelfth day. It is probable that the
average duration of fatal cases is from twenty-four to thirty-six hours.
_Symptoms._--In the majority of cases the symptoms commence immediately,
with an acrid metallic taste, often described as coppery, and a sense of
constriction and burning heat in the throat and stomach. The burning
pain gradually extends over the abdomen, and is much increased by
pressure. There is nausea, with vomiting of the contents of the stomach.
These matters are sometimes mixed with blood and stringy masses of
mucus. The sickness is accompanied by diarrhoea or dysentery, swelling
of the abdomen, and increased pain. The countenance becomes flushed and
often swollen, though it is occasionally pallid and anxious; the lips
and tongue get white and shrivelled; there is frequently some
dyspnoea, while the pulse is small, or wiry and frequent; and death is
preceded by faintness, cramps, insensibility, or convulsions.
Should these effects not prove rapidly fatal, the pain will gradually
become lessened, though attacks of colic and nausea may come on at
intervals for several days. Often the secretion of urine is almost, or
even quite, suppressed. After a time there are symptoms of hectic fever,
with much depression. The gums and salivary glands also become swollen,
there is a coppery taste in the mouth, the breath is very foetid, and
there is severe ptyalism or salivation. This latter effect is the most
prominent feature in the _chronic_ form of poisoning, where small and
frequently-repeated doses have been given: it often proceeds to such an
extent as to cause death, when the patient would otherwise probably
recover.
It must not be forgotten that salivation sometimes arises where no
mercurial of any kind has been given. Thus arsenic, bismuth, lead,
iodide of potassium, opium, &c., may induce it in some very peculiar
constitutions. Small medicinal doses (as a few grains of calomel) may
also excite it in certain susceptible individuals; and especially in
persons suffering from renal disease. It may also occur spontaneously,
as in stomatitis or inflammation of the mouth; and very troublesome
examples of it may occur in pregnant women.
It is strange that neither in acute nor chronic mercurial poisoning do
we observe any marked loss of muscular power. Yet workers in quicksilver
(owing to the absorption of the fumes of mercury during respiration) are
very apt to suffer from a peculiar kind of paralysis; which commences
with inability to direct the hands and arms, and goes on to a shaking or
trembling of all parts of the body.
_Post-mortem Appearances._--The appearances produced by corrosive
sublimate are confined chiefly to the digestive canal. The mucous
membrane of the mouth, fauces, and oesophagus is softened and of a
whitish or bluish-grey color. The stomach also presents marks of violent
inflammation; beneath the mucous membrane numerous patches of
extravasated blood are seen, and frequently corrosion or ulceration has
been found. The large and small intestines, the peritoneum, and
especially the urinary organs, often appear inflamed. In many instances
the bladder has been much contracted.
_Treatment._--This must consist in the removal of the poison and the
administration of antidotes. Vomiting is best promoted by administering
copious draughts of fluids containing albumen: but if necessary
ipecacuan may be given. The white and the yolk of raw eggs with milk
should be abundantly administered. Gluten has been much recommended, and
may readily be prepared by washing flour in a muslin bag under a stream
of water; but on an emergency it will be best to exhibit the flour at
once, made into a paste with milk or water. The free use of demulcent
drinks, milk, and ice will be very grateful to the patient's feelings.
Gargles of alum or borax do some good. Opiates may be given in small
doses, if there be much pain, and we should allow only a milk or
farinaceous diet. Sucking chlorate of potash has been recommended to
check the salivation. The most useful remedy, however, is the iodide of
potassium; for this salt destroys the compounds formed by the union of
mercury with certain of the tissues, and eliminates the poison through
the kidneys.
_Tests._--Corrosive sublimate is completely volatilized by heat.
1. Liquor potassae added to its solution gives a yellow precipitate. This
precipitate, if washed, dried, and heated in a test tube, gives a ring
of metallic mercury in the form of globules in the cool part of the
tube. In like fashion corrosive sublimate itself may be reduced and
volatilized if heated with black flux.
2. On adding a solution of iodide of potassium to a small quantity of
the solution, a bright scarlet precipitate, soluble in excess of iodide
of potassium, is produced.
3. If a drop or two of a solution of corrosive sublimate, slightly
acidulated with hydrochloric acid, be placed on a sovereign, and the
solution and the gold be touched with a piece of zinc or an iron key,
the mercury will be deposited as a bright silvery stain on the gold.
CALOMEL (_Subchloride_ or _Chloride of Mercury_) is a heavy white
powder, which is usually regarded as a safe medicine. Yet, in some
peculiar constitutions, it has caused excessive salivation and death,
even though only a few grains have been given. In large doses it may be
regarded as an irritant poison. It is distinguished from corrosive
sublimate by forming a black precipitate with caustic potash and by its
insolubility in water.
AMMONIO CHLORIDE OF MERCURY (_White Precipitate_).--This substance is a
chalky looking powder, containing about eighty per cent. of mercury. It
produces vomiting, purging, great pain in the stomach, cramps, and
convulsions. Out of fourteen cases, collected by Dr. Taylor, in which
from a few to forty grains were taken, only two proved fatal.
The remaining preparations of mercury, which in rare instances have been
used as poisons, are the _Red Oxide of Mercury_ (red precipitate); the
_Red Sulphuret of Mercury_ (cinnabar or vermilion); the _Cyanide of
Mercury_; the _Nitrates of Mercury_; and _Turpeth Mineral_.
Mercury may be separated from organic admixture by Reinsch's method.