Sulphate of zinc is said to have proved fatal when applied externally. In Pyl’s memoirs there is a case of this nature, which was attributed to sulphate of zinc having been used as a lotion for a scabby eruption on the head. The subject was a child, six years old, and otherwise healthy. The wash, which was a vinous solution, had not been long applied before the child complained of acute burning pain of the head, which was followed by vomiting, purging, convulsions, and death in five hours. The cause of these symptoms, though the particulars of the case were ascertained judicially by an able medical jurist, Dr. Opitz of Minden, is nevertheless very doubtful, as daily use is made of the salt for similar purposes without any such effect. Appearances of congestive apoplexy were found within the skull; and the reporter ascribes death to the wash having produced repulsion of the cutaneous disease, and determination of blood to the head.[[1211]]
The only opportunities which have occurred of observing the morbid appearances after poisoning with sulphate of zinc taken internally, are the cases by Metzger, Mertzdorff, and Werres.
In the first, which was a mixed case, the only appearances of note were slight inflammation in the stomach, and excessive gorging of the lungs with fluid blood; from which Metzger oddly enough concludes that the child was suffocated by the vomiting. In the second case, Mertzdorff found the stomach and intestines, but particularly the latter, contracted,—their outer surface healthy—the inner membrane of the stomach grayish-green, with several spots of effused blood, and greenish, fluid contents,—the inner membrane of the small intestines similarly spotted,—the rest of the body quite natural. It has been already mentioned that Mertzdorff detected the poison in the body. He found it not only in the contents, but likewise in the coats of the stomach and intestines. In the third, Werres found a reddish-brown patch and some vascularity in the stomach.
Of Poisoning with Iron.
In previous editions of this work the preparations of iron were arranged among those substances which are not usually considered poisonous, but which may nevertheless prove injurious when taken in large quantity. But the soluble salts of iron, although not very active, seem sufficiently so to entitle them to a regular place among poisons; and one of them, the sulphate, has actually been used, as will presently appear, for the purpose of committing murder. There are many soluble salts of iron which in all probability may prove hurtful; but the only ones which have been brought under notice in medico-legal researches are the sulphate of the protoxide, and the mixed chlorides.
The sulphate of the protoxide of iron, commonly called green vitriol or copperas, occurs in commerce in crystals or crystalline masses of various shades of bluish-green. It is easily known by its colour and its strong styptic inky taste. When in solution, the iron may be detected by ferro-cyanate of potash, sulphuretted-hydrogen, and tincture of galls. Ferro-cyanate of potash causes a blue precipitate, at first pale, but gradually passing to deep Prussian blue. Sulphuretted-hydrogen has no effect, but if an alkali, such as ammonia, be added to disengage the oxide of iron, a black precipitate of sulphuret of iron is immediately produced. Tincture of galls occasions a deep purplish-black precipitate, the tannate of iron, and it acts with greater delicacy in very diluted solutions, if the oxide of iron be disengaged by carbonate of soda. These tests prove the presence of iron in solution. A white precipitate under the action of nitrate of baryta will indicate that the oxide is dissolved by sulphuric acid.
The most familiar form of chloride of iron is the tincture of the chloride, which sometimes contains only the sesquichloride, sometimes consists of a mixture of this with the protochloride. It is known by the three tests for oxide of iron described above, and by nitrate of silver occasioning a heavy white precipitate, insoluble in nitric acid.
For detecting iron in organic mixtures, where the liquid reagents do not act satisfactorily, the simplest process is to digest the mixture, if there be any solid matter, in water acidulated with acetic acid, to evaporate the filtered liquid to dryness, to incinerate the extract in a porcelain crucible, to act on the product with diluted sulphuric acid, and then to treat the solution with the three liquid reagents.
Professor Gmelin found that sulphate of iron merely caused vomiting in dogs who were made to swallow two drachms of it, that rabbits might take forty grains without any apparent injury, and that twenty grains in a state of solution might even be injected into the veins of a dog without producing any particular symptom.[[1212]] From these and some other facts of the like kind it was generally held, that sulphate of iron is not a poison. But Smith ascertained that a dose of two drachms will prove fatal to dogs in little more than twenty-tour hours, when it is introduced into the stomach, and in half that time if applied to a wound; and that it occasions some redness of the alimentary mucous membrane, and the effusion of a thick layer of tough mucus. It is remarkable, however, that, like Gmelin, he found no effect to flow from the transfusion of a solution of seven grains into the veins, except transient vomiting and expressions of pain.[[1213]]
The effects which have been observed in the human subject are conformable with those witnessed in experiments on the lower animals, the symptoms being those of pure irritant poisoning. Few illustrative cases, however, have as yet been made public. In Rust’s Journal there is the case of a girl, who took as an emmenagogue, an ounce of green vitriol dissolved in beer, and suffered in consequence from colic pains, constant vomiting and purging for seven hours, but eventually recovered under the use of mucilaginous and oily drinks.[[1214]] A fatal case of poisoning with this substance occurs in the Parliamentary Returns of death from poison in England during the years 1837–38 [see p. [90]].—Dr. Combe of Leith has communicated to me an instructive case of fatal poisoning with the tincture of the chloride of iron, which was taken to the extent of an ounce and a half by a gardener accidentally instead of whisky. Violent pain in the throat and stomach, tension and contraction of the epigastrium, and nausea immediately ensued; afterwards coldness of the skin and feebleness of the pulse were remarked; and then vomiting of an inky fluid, with subsequently profuse vomiting of mucus and blood, and also bloody stools under the use of laxatives. He remained for some days in a very precarious state, but then began to rally, and in three weeks resumed his occupation. But in two weeks more Dr. Combe found him emaciated, cadaverous in appearance, and affected with pains in the stomach, costiveness, and thirst; in which state he lingered for five days more, and then died. In the dead body there was found great thickening towards the pylorus, a cicatrized patch there three inches long and two inches broad, and another large patch of inflammatory redness surrounded by a white border. The preparation taken in this instance contained a third of its volume of hydrochloric acid and a tenth of its weight of oxide of iron; and consequently some of the acid was free.