THE CONCENTRATED MINERAL ACIDS.
The first division of the Corrosive consists of the Strong Mineral
Acids. In this chapter we have to review the effects, &c., of the acids
commonly encountered, which are Sulphuric Acid, Nitric Acid,
Hydrochloric Acid, or a mixture of two or more of them.
SULPHURIC ACID (_Oil of Vitriol_).--This heavy, oily looking liquid is
met with in two states, concentrated and diluted; and being extensively
employed in commerce and manufactures is much more frequently used as a
poison than the other mineral acids. Many infants and young children
have been poisoned by it; occasionally also men, under the influence of
drink. The acid is not unfrequently thrown over the person, either to
disfigure the features or to destroy the clothes. The parts of the body
with which it is brought into contact are stained at first of a white,
and afterwards of a dark brown or black color. The smallest fatal dose
of concentrated acid recorded, in the adult, is one drachm; but recovery
has taken place after as much as two ounces. But it must be understood
that the acid proves fatal mainly by its power of corrosion, so that a
small dose of the concentrated acid is more dangerous than is a much
larger dose of it in the dilute form. The average period at which death
occurs is from sixteen to twenty-four hours; but on the other hand,
death may not occur for months, and may only follow the organic changes
induced by cicatrization following the swallowing of the acid, or the
malnutrition following its destructive action on the coats of the
stomach.
_Tests._--It is not within the province of these Memoranda to treat of
the various processes by which poisons are to be detected; for to make a
trustworthy analysis requires the skill of a professed chemist, whose
assistance should be allowed in these medico-legal investigations. Where
the character of a dead man or the life of a supposed criminal is at
stake there must be no chance of error. The ordinary tests will,
however, be briefly described, if only to help the physician to treat
the case more satisfactorily than he could do by merely guessing that an
irritant or narcotic had been employed:
Concentrated sulphuric acid is usually a brownish colored liquid, which
chars or corrodes wood or other organic matter brought into contact with
it, and when mixed with water gives out heat. When diluted, its presence
may be thus detected:
1. The liquid is known to be acid by its action on litmus paper.
2. Add to a portion of the suspected liquid a few drops of nitric acid,
and then a solution of nitrate of barium; a white precipitate (sulphate
of barium) will fall if sulphuric acid be present. This test is
extremely delicate; for although other acids yield a precipitate on the
addition of nitrate of barium, yet as such deposits are all soluble in
nitric acid the previous addition of this acid will prevent their
formation.
3. The precipitate should next be collected, dried, and reduced with
charcoal by the blow-pipe flame to the condition of barium sulphide.
This, when treated with a drop of hydrochloric acid, gives off
sulphuretted hydrogen, known by blackening paper dipped in acetate of
lead solution.
To examine a piece of cloth stained with this poison it is only
necessary to boil it in distilled water and then apply to the liquid the
barium test as before.
NITRIC ACID (_Aqua fortis_, _Red Spirit of Nitre_).--This substance has
been employed as a poison for upwards of four centuries. Like the oil of
vitriol it is found in commerce in a concentrated and in a diluted
state. Cases of poisoning by it are rare. It produces a yellow stain on
the skin. Two drachms is the smallest quantity which has destroyed life;
but less than this would probably prove fatal, if it produced much
corrosion about the wind-pipe. Death has occurred from it, in one hour
and three quarters; the average would be within twenty-four hours.
Several cases ending fatally have followed the inhalation of the fumes
of this acid, probably by inducing very extensive inflammation of the
lung.
_Tests._--The concentrated acid may be known by its orange-colored
irritating fumes, and by its action on copper, tin, or mercury.
1. When poured on copper-filings, effervescence takes place, a red acid
vapor is given off, and a green liquid remains (solution of nitrate of
copper).
2. In a diluted state it is detected by its acid reaction; by no
precipitate being obtained by nitrate of barium or by nitrate of silver,
proving the absence of sulphuric and hydrochloric acids; further, by
neutralizing the liquid with potass, evaporating it, and then procuring
crystals of nitrate of potassium, in the form of lengthened fluted
prisms, which are permanent in the air. These crystals may be powdered
and moistened with strong sulphuric acid, when a colorless acid vapor
(nitric acid) will be evolved. Or the powdered crystals may be mixed
with an equal bulk of fine copper filings, moistened with water, and
treated with a few drops of sulphuric acid; when ruddy acid fumes will
be given off.
3. Other tests for nitric acid are, (_a_,) its action on morphia, which
it turns red: (_b_,) its action on green iron sulphate, which it
blackens; (_c_,) a trace of it along with sulphuric acid gives with
narcotine a blood red color; and finally, (_d_,) along with hydrochloric
acid it dissolves gold.
HYDROCHLORIC ACID (_Muriatic Acid_, _Spirit of Salt_).--Not more than
half a dozen cases of poisoning by this acid have occurred in the last
fifteen or twenty years in this country. In May, 1859, a woman
sixty-three years old was admitted into King's College Hospital within
three-quarters of an hour of swallowing half an ounce of the strong
acid. She had burning pain in the throat and stomach, vomiting of brown
shreddy matters, and great prostration. Death occurred in eighteen
hours, from the corrosive action of the poison. This is the smallest
dose which has been known to prove fatal.
_Tests._--The concentrated hydrochloric acid of commerce is of a
yellowish color, it fumes in the air when strong, and produces dense
white fumes with the vapor of ammonia.
1. It may be identified by boiling with black oxide of manganese;
chlorine being given off, which is known by its odor, color, and
bleaching properties.
2. When diluted, its presence is ascertained by nitrate of silver
causing a dense white precipitate (chloride of silver). The chloride is
distinguished from other salts of silver by (_a_,) its insolubility in
nitric acid, and in caustic potass; (_b_,) by its being soluble in
ammonia; (_c_,) by its melting and forming a horny mass when dried and
heated.
MIXED ACIDS.--These acids being used for commercial purposes when
mixed--_the nitro-muriatic_ (aqua regia) to dissolve gold, and the
_nitro-sulphuric_ (aqua reginae) to dissolve silver--might occasion their
being employed as poisons. _Sulphate of indigo_, which consists of a
solution of indigo in strong sulphuric acid, has proved fatal in cases
where it has been accidentally taken.
_Symptoms, Treatment, &c._--The _symptoms_ produced by the mineral acids
are much the same in all cases. There is violent, burning pain in the
mouth, oesophagus, and stomach, commencing _immediately_. The burning
is followed by retching and vomiting of a dark colored liquid with
shreds of mucus, and portions of the mucous membrane of the oesophagus
or stomach. The inside of the mouth is shrivelled and more or less
corroded unless the agent has been given in a spoon or otherwise passed
over the tongue to the back of the fauces. The outside of the lips and
mouth will probably present the stains characteristic of the acid used.
There is great thirst, difficulty of swallowing, and impeded
respiration. The bowels are confined; the urine scanty or suppressed.
Next succeeds great exhaustion, the pulse becomes quick and feeble, and
the skin gets cold and clammy. The countenance is anxious and expressive
of great suffering; death speedily occurs, the intellectual faculties
remaining clear to the last.
These acids may prove fatal without entering the stomach by causing
asphyxia, the chink of the glottis becoming closed by swelling of the
fauces, &c. They have sometimes been administered by the vagina, rectum,
&c., and been poured into the ear during sleep.
Where recovery takes place from their immediate effects there is always
fear of death resulting at the end of one or two years from stricture of
the oesophagus, and even at an earlier period, unless proper treatment
is adopted. Occasionally one of the secondary effects of sulphuric acid
has been profuse salivation.
The _post-mortem appearances_ are the following: The body may have a
healthy appearance. Usually there are stains about the mouth, fingers,
and wherever the cuticle has been reached by the acid. The inner surface
of the mouth, fauces, and oesophagus, is usually white and corroded,
or dark brown and shrivelled, the mucous coat being easily detached. The
epiglottis and glottis are usually swollen. The gullet resembles the
mouth in most respects. The outer surface of the stomach and intestines
is very vascular, that of the former being sometimes corroded and
occasionally perforated. The stomach is sometimes contracted, sometimes
distended with gas, and contains a thick, dark brown fluid; its inner
surface has a charred, blackened appearance, the mucous membrane between
the rugae being of a scarlet hue. The pylorus is mostly contracted; while
the inner coat of the duodenum and small intestines presents a similar
appearance, in a less degree, to that of the stomach. When perforation
occurs it usually takes place posteriorly, and the edges of the rent are
softened. The escaped matters may have acted on the adjacent viscera.
According to Casper, after poisoning by sulphuric acid the bodies resist
putrefaction for some time, owing perhaps to the acid neutralizing the
ammonia of decomposition. It may be the same with the other mineral
acids.
_Treatment._--Bicarbonate of soda, or calcined magnesia, or the
carbonate of magnesia, should be immediately given, mixed in milk or any
mucilaginous fluid; the doses being continued at short intervals, until
it may be inferred that the acid is neutralized. In the absence of these
remedies substitutes may be found in chalk, whiting, soap and water, or
the plaster of the apartment beaten up with water. Oleaginous and
mucilaginous fluids, as olive oil, linseed tea, barley water, milk
gruel, &c., may be freely given, either alone, or as the vehicles of the
antidote. The success of this treatment will depend upon the promptitude
with which it is adopted.
The stomach pump should not be employed; the disorganized and softened
state of the gullet and stomach, rendering them excessively liable to
perforation.
Should the larynx be affected and the breathing impeded, tracheotomy
must be at once had recourse to.
After a sufficiency of the antidote has been given the use of
mucilaginous diluents must be continued for some time, and the
subsequent treatment will be that for gastro-enteritis. Great benefit
will be derived from the use of oily enemata.
The external parts which have been injured by the acid should be well
bathed with soap and water, and treated like burns.