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 reginæ) 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, œsophagus, 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 œsophagus 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 œsophagus, 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 œsophagus, 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 rugæ 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.