PART IX.—INORGANIC POISONS. (continued 4)

Compound Mercury Ointment (Unguentum hydrargyri compositum).—Made with ointment of mercury, yellow wax, olive oil, and camphor; it should contain 22·2 per cent. Hg.

Liniment of Mercury (Linimentum hydrargyri) is made of mercurial ointment, solution of ammonia, and liniment of camphor; it contains about 16¹⁄₂ per cent. of mercury.

Mercurial Suppositories (Suppositoria hydrargyri).—Composed of ointment of mercury and oil of theobroma. Each suppository should weigh 15 grains and contain ¹⁄₃ of its weight of mercurial ointment.

Acetate of Mercury (Mercurous acetate) is not contained in the B.P., but is officinal on the Continent. It is a salt occurring in white micaceous scales, soluble in 133 parts of cold water, giving the reactions of acetic acid and mercury, and very readily decomposed.

Mercuric Ethyl Chloride (Hydrargyrum æthylo-chloratum) is used as a medicine on the Continent. It occurs in white, glittering, crystalline scales, which take on pressure a metallic appearance, and possess a peculiar ethereal odour; it is but little soluble in water and ether, with difficulty in cold alcohol, but copiously soluble on boiling, and depositing crystals on cooling. It sublimes at about 40° without residue; on quick heating it burns with a weak flame, developing a vapour of metallic taste and unpleasant odour. It gives no precipitate with silver nitrate, nor with albumen.

Corrosive Sublimate (Mercuric chloride), HgCl₂ = 271; Hg, 73·8 per cent., Cl, 26·1 per cent.—In commerce this salt occurs in transparent, heavy, colourless masses, which have a crystalline fracture; if placed in the subliming cell described at p. 258, it sublimes at about 82·2° (180° F.), and melts at higher temperatures. The sublimate is generally in groups of plates drawn to a point at both ends, in crystalline needles, or in octahedra with a rectangular base. It dissolves in 16 parts of cold water and about 3 of boiling, and is very soluble in solutions of the alkaline chlorides; it dissolves also in ether, and can be, to a great extent, withdrawn from aqueous solutions by this agent. Alcohol dissolves nearly one-third its weight of the salt, and its own weight when boiling. It combines with albumen; gives, when in solution, a precipitate of mercuric oxide when tested with solution of potash; a white precipitate with ammonia; a scarlet with iodide of potassium; and a black precipitate of finely divided mercury with protochloride of tin. If a crystal (when placed in the subliming cell) gives a crystalline sublimate at about the temperature mentioned, and this sublimate becomes of a red colour when treated with a droplet of iodide of potassium, it can be no other substance than corrosive sublimate.

Solution of Perchloride of Mercury (Liquor hydrargyri perchloridi) is simply 10 grains of perchloride of mercury and chloride of ammonium in a pint of water; 100 c.c. therefore should contain 114 mgrms. corrosive sublimate.

Yellow Mercurial Lotion (Lotio hydrargyri flava).—Perchloride of mercury, 18 grains, mixed with 10 ounces of solution of lime.

Calomel[903] (Hydrargyri subchloridum).—The properties of calomel have been already described. It sometimes contains as an impurity corrosive sublimate, which may be dissolved out by ether. Carbonate of lead, sulphate, and carbonate of baryta, gum, and starch, are the usual adulterants mentioned. If on the application of heat calomel entirely sublimes, it must be free from the substances enumerated.

Oleate of Mercury (Hydrargyri oleatum) is composed of 1 part of yellow oxide and 9 parts of oleic acid.

Black Mercurial Lotion (Lotio hydrargyri nigra).—Calomel, 30 grains, mixed with 10 fluid ounces of lime-water.

Compound Pill of Subchloride of Mercury.—Calomel and sulphurated antimony, each 1 ounce, guiac resin 2 ounces, castor-oil 1 fluid ounce. One grain (·0648 grm.) of calomel, and the same quantity of antimony sulphide, are contained in every 5 grains (324 mgrms.) of the pill mass, i.e., calomel 20 per cent.

Ointment of Subchloride of Mercury (Unguentum hydrargyri subchloridi).—Calomel mixed with benzoated lard; strength about 1 : 6¹⁄₂.

White Precipitate (Hydrargyrum ammoniatum, NH₂HgCl).—A white, heavy powder, subliming by heat without residue, and insoluble in water, alcohol, and ether. With soda, it yields a metallic sublimate. When boiled with potash, ammonia is evolved, the yellow oxide of mercury formed, and chloride of potassium passes into solution. It should contain 79·5 per cent. of mercury.

The fusible white precipitate of the pharmacopœia of the Netherlands does not appear to be of constant composition, varying between 69·4 to 65·6 per cent. of mercury.[904] It melts on heating, and leaves as a residue chloride of sodium.

Commercial white precipitate is frequently adulterated; Barnes has found carbonates of lead and lime, the latter to the extent of nearly 2 per cent.[905] Calomel, according to Nickles,[906] has been substituted for white precipitate, but this was several years ago. The methods for detection are obvious.

Ointment of Ammoniated Mercury (Unguentum hydrargyri ammoniati).—1 part of ammoniated mercury mixed with 9 parts of simple ointment.

Red Iodide of Mercury (Hydrargyrum iodidum rubrum, HgI₂).—A crystalline powder of a scarlet colour, becoming yellow on gentle heating. It is very insoluble in water, one part requiring from 6000 to 7000 parts; soluble in 130 parts of cold, 150 of hot alcohol; and dissolving freely in ether, or in aqueous solution of iodide of potassium.

Ointment of Red Iodide of Mercury (Unguentum hydrargyri iodidi rubri).—16 grains of the substance mixed with an ounce of simple ointment.

Green Iodide of Mercury (Hydrargyri iodidum viride, HgI).—A dingy, greenish-yellow powder, darkening on exposure to light, and easily decomposed into the red iodide.

Red Oxide of Mercury (Hydrargyri oxidum rubrum), HgO = 216; Hg, 92·12 per cent.; specific gravity, 11 to 11·3; small, red, shining, crystalline scales, very insoluble in water, requiring about 20,000 parts; entirely soluble in hydrochloric acid. By a heat below redness it may be volatilised, and at the same time decomposed into mercury and oxygen. Its principal impurity is nitric acid, readily detected by the usual tests, or by heating in a test-tube, when, if nitric acid is present, orange vapours will be evolved. Fixed red powders (such as brick-dust and minium) are detected by being left as a residue, after the application of heat sufficient to volatilise the mercury. An ointment (strength 1 : 8) is officinal.

Sulphate of Mercury.—A white crystalline powder, decomposed by water into the very insoluble basic salt of mercury, known as Turbith mineral, HgSO₄2HgO.

Turbith, or Turpeth, Mineral is contained in the French pharmacopœia, HgSO₄2HgO; Hg, 82·4 per cent.; specific gravity, 8·319. It requires for solution 2000 parts of cold, and 600 of boiling water; but dissolves with tolerable ease in hydrochloric acid.

The Sulphide of Mercury, known in commerce under the name of Ethiops mineral, is officinal in France, the Netherlands, and Germany. Its properties have been already described. The German and Dutch pharmacopœias require in it 50, the French only 33¹⁄₃ per cent. of metallic mercury.

Hahnemann’s Soluble Mercury (Hydrargyrum solubile Hahnemanni) is officinal in the Dutch pharmacopœia. As found in commerce it contains metallic mercury, nitric acid, and ammonia. The mercury should be in the proportion of 86·33 per cent., the ammonia 2·44 per cent.

Crystallised Nitrate of Mercury (Hydrargyrum nitricum oxidulatum) is officinal in the pharmacopœias of Germany, Switzerland, and France. The salt is in white crystals, giving the reactions of nitric acid and mercury, decomposed by the addition of water, but fully soluble in water, if first moistened with nitric acid. The formula of the neutral salt is Hg2NO₃HgO2H₂O, which requires 69·4 per cent. of mercury. An acid solution of mercuric nitrate is officinal.

An Ointment of Nitrate of Mercury (Unguentum hydrargyri nitratis) (often called citrine ointment) is contained in the B.P.; it is made with 4 parts of mercury, nitric acid 12, lard 15, olive oil, 32; the strength is about 1 in 15¹⁄₂.

A Chloride of Mercury and Quinine exists in commerce, prepared by mixing 1 part of corrosive sublimate in solution with 3 parts of quinine chloride, evaporating, and crystallising.

Cyanide of Mercury, HgCy, is contained in the French pharmacopœia. It occurs in small, colourless, prismatic crystals, easily soluble in water. If to the solution chloride of tin be added, a black precipitate of reduced metal and stannous oxide is thrown down, and the odour of prussic acid is developed.

Mercuric Sulphide (Sulphide of Mercury, Cinnabar, Vermilion) is officinal in Germany, the Netherlands, and France; HgS = 232; specific gravity, solid, 8·2; Hg, 86·21 per cent., O, 13·79 per cent. For medicinal purposes it is made artificially. It is a beautiful red powder, insoluble in all alkaline and all acid liquids, with the exception of aqua regia. The solution gives the reactions of a sulphide and mercury. On heating, it must burn away entirely without residue; adulterations or impurities are—minium, lead, copper, and other metals. The detection of minium is conveniently executed in the dry way. Pure cinnabar, when heated in a matrass, gives a black sublimate, which becomes red on friction. If minium is present, sulphide of lead remains as a residue, and may be recognised on coal; the same remark applies to sulphide of antimony. If it be desired to take the percentage of mercury in cinnabar, equal parts of oxalate and cyanide of potassium should be well mixed with the cinnabar, and heated in the bent tube described at p. 654; by this means the whole of the metallic mercury is readily obtained.[907]

§ 831. Mercury in the Arts.—The use of mercury in the arts is so extensive, that any one in analytical practice is almost certain occasionally to meet with cases of accidental poisoning, either from the vapour[908] or some of its combinations.

Quicksilver is used in the extraction of gold, the silvering of mirrors, the construction of barometers, and various scientific instruments and appliances; also for the preservation of insects, and occasionally for their destruction.[909] An alloy with zinc and cadmium is employed by dentists for stopping teeth; but there is no evidence that it has been at all injurious, the mercury, probably, being in too powerful a state of combination to be attacked by the fluids in the mouth.[910] Cinnabar has also been employed to give a red colour to confections, and it may be found in tapers, cigarette papers, and other coloured articles. The nitrate of mercury in solution finds application in the colouring of horn, in the etching of metals, in the colouring of the finer sorts of wool, and in the hat manufacture.

The sulphocyanide of mercury gives, when burnt, a most abundant ash, a fact utilised in the toy known as Pharaoh’s serpent; the products of combustion are mercurial vapours and sulphurous anhydride. That the substance itself is poisonous, is evident from the following experiment:—·5 grm. was given to a pigeon without immediate result; but ten hours afterwards it was indisposed, refused its food, and in forty hours died without convulsions.[911]

§ 832. The more Common Patent and Quack Medicines containing Mercury.

Mordant’s Norton’s Drops.—This patent medicine is a mixture of the tincture of gentian and ginger, holding in solution a little bichloride of mercury, and coloured with cochineal.

Solomon’s Anti-impetigines is a solution of bichloride of mercury, flavoured and coloured.

Poor Man’s Friend.—An ointment of nitrate of mercury.

Brown’s Lozenges.—Each lozenge contains ¹⁄₂ grain of calomel, and 3¹⁄₂ grains of resinous extract of jalap; the rest is white sugar and tragacanth.

Ching’s Worm Lozenges.—Each lozenge contains 1 grain of calomel; the rest white sugar and tragacanth, with saffron as a colouring matter.

Storey’s Worm Cakes.—Each cake 2 grains of calomel, 2 grains of cinnabar, 6 grains of jalap, 5 grains of ginger, and the remainder sugar and water.

Wright’s Pearl Ointment is said to be made up of 8 ozs. of white precipitate rubbed to a cream in 1 pint of Goulard’s extract, and to the mixture is added 7 lbs. of white wax and 10 lbs. of olive oil.

Keyser’s Pills.—The receipt for these pills is—red oxide of mercury 1¹⁄₂ oz., distilled vinegar (dilute acetic acid) 1 pint; dissolve, add to the resulting solution manna 2 lbs., and triturate for a long time before the fire, until a proper consistence is attained; lastly, divide the mass into pills of 1¹⁄₂ grain each.

Mitchell’s Pills.—Each pill contains aloes ·8 grain, rhubarb 1·6 grain, calomel ·16 grain, tartar emetic ·05 grain.

Many Antibilious Pills will be found to contain calomel, a few mercury in a finely divided state.

§ 833. Mercury in Veterinary Medicine.—Farmers and farriers use the ointment (blue ointment) to a dangerous extent, as a dressing for the fly, and wholesale poisoning of sheep has been in several instances the consequence.[912] Ethiops mineral and Turpeth mineral are given to dogs when affected by the distemper, worms, or the mange. Mercury, however, is not very frequently given to cattle by veterinary surgeons, ruminants generally appearing rather susceptible to its poisonous effects.

§ 834. Medicinal and Fatal Dose—Horses.—Cinnabar 14·2 grms, (¹⁄₂ oz.), calomel 14·2 grms. (¹⁄₂ oz.) or more, corrosive sublimate ·13 to ·38 grm. (2 to 6 grains), and as much as 1·3 grm. (20 grains) have been given in farcy.

Cattle.—Mercury with chalk 3·8 to 11·6 grms. (1 to 3 drms.), calomel 3·8 to 7·7 grms. (1 to 2 drms.) for worms; ·65 to 1·3 grm. (10 to 20 grains) as an alterative; Ethiops mineral, 7·7 to 15·5 grms. (2 to 4 drms.).

Dogs.—Ethiops or Turpeth mineral ·13 to 1·3 grm. (2 to 20 grains), according to the size.

Fowls.—Mercury and chalk are given in fractions of a grain.

Hogs are also treated with mercury and chalk; the dose usually given does not exceed ·32 grm. (5 grains).

It may be remarked that many of the doses quoted appear very large; the writer cannot but consider that 20 grains of corrosive sublimate administered to a horse would be more likely to kill the animal than to cure the disease.

Man.—Corrosive sublimate has been fatal in a dose so small as ·19 grm. (3 grains); white precipitate has caused dangerous symptoms in doses of from 1·9 to 2·6 grm. (30 to 40 grains); the cyanide of mercury has killed a person in a dose of ·64 grm. (10 grains)—Christison; and Turpeth mineral has proved fatal in doses of 2·6 grms. (40 grains).

Other preparations of mercury have also been fatal, but a doubt has existed as to the precise quantity. Sometimes, also, there is probably a chemical change in the substance, so that it is impossible to state the fatal dose. For example, it is well known that calomel, under the influence of alkaline chlorides, can be converted into the bichloride—a fact which probably explains the extensive corrosive lesions that have been found after death from large doses of calomel.

§ 835. Poisoning by Mercury—Statistics.—In the Registrar-General’s death returns for the ten years ending 1892, it appears that in England the deaths from mercurial poisoning[913] were 40 males, 19 females; of these, 16 males and 18 females were cases of suicide, the remainder were referred to accident.

The effects of the different compounds of mercury may be divided into two groups, viz., (1) Those caused by the finely divided metal and the non-corrosive compounds; (2) the effects caused by the corrosive compounds.

§ 836. (1) Effects of Mercurial Vapour, and of the Non-Corrosive Compounds of Mercury.

(a) Vegetable Life.—Priestly and Boussingault have shown that plants under a glass shade in which mercury is exposed in a saucer, first exhibit black spots on the leaves; ultimately, the latter blacken entirely, and the plants die.

(b) Animal Life.—Mercury in the form of vapour is fatal to animal life, but it is only so by repeated and intense application. Eulenberg[914] placed a rabbit under a large glass shade, and for four days exposed it daily for two hours to the volatilisation of 2 grms. of mercury on warm sand; on the sixth and seventh day 1·5 grm. was volatilised. On the fifteenth day there was no apparent change in the aspect of the animal; 5 grms. of mercury were then heated in a retort, and the vapour blown in at intervals of ten minutes. Fourteen days afterwards the gums were reddened and swollen, and the appetite lost; the conjunctivæ were also somewhat inflamed. The following day these symptoms disappeared, and the animal remained well.

In another experiment 20 grms. of mercury were volatilised, and a rabbit exposed to the vapour under a small glass shade. The following day the conjunctivæ were moist and reddened; two days afterwards 10 grms. of mercury were volatilised in the same way; and in two days’ interval other 10 grms. were volatilised in three-quarters of an hour. There was no striking change noticeable in the condition of the animal, but within forty-eight hours it was found dead. The cause of death proved to be an extravasation of blood at the base of the brain. The bronchia were reddened throughout, and the lungs congested. Mercury, as with man, is also readily absorbed by the broken or unbroken skin; hence thousands of sheep have been poisoned by the excessive and ignorant external application of mercurial ointment as a remedy against the attacks of parasites. The sheep become emaciated, refuse food, and seem to be in pain, breathing with short quick gasps.

In experiments on rabbits, dogs, and warm-blooded animals generally, salivation and stomatitis are found to occur as regularly as in man; so also in animals and man, paralytic and other nervous affections have been recorded.

§ 837. (c) Effects on Man.—In 1810[915] an extraordinary accident produced, perhaps, the largest wholesale poisoning by mercurial vapour on record. The account of this is as follows:—H.M.S. “Triumph,” of seventy-four guns, arrived in the harbour of Cadiz in the month of February 1810; and in the following March, a Spanish vessel, laden with mercury for the South American mines, having been driven on shore in a gale, was wrecked. The “Triumph” saved by her boats 130 tons of the mercury, and this was stowed on board. The mercury was first confined in bladders, the bladders again were enclosed in small barrels, and the barrels in boxes. The heat of the weather, however, was at this time considerable; and the bladders, having been wetted in the removal from the wreck, soon rotted, and mercury, to the amount of several tons, was speedily diffused as vapour through the ship, mixing more or less with the bread and the other provisions. In three weeks 200 men were affected with ptyalism, ulceration of the mouth, partial paralysis, and, in many instances, with diarrhœa. The “Triumph” was now ordered to Gibraltar, the provisions were removed, and efforts were made to cleanse the vessel. On restowing the hold, every man so employed was salivated. The effects noted were not confined to the officers and ship’s company, for almost all the stock died from the fumes—mice, cats, a dog, and even a canary bird shared the same fate, though the food of the latter was kept in a bottle closely corked up. The vapour was very deleterious to those having any tendency to pulmonic affections. Three men, who had never complained before they were saturated with mercury, died of phthisis; one, who had not had any pulmonic complaint, was left behind at Gibraltar, where his illness developed into a confirmed phthisis. Two died from gangrene of the cheeks and tongue. A woman, confined to bed with a fractured limb, lost two of her teeth; and many exfoliations of the jaw took place.

Accidents from the vapour of mercury, quite independently of its applications in the arts, have also occurred, some of them under curious circumstances; such, for example, is the case mentioned in the footnote to p. 639. Witness, again, a case mentioned by Seidel,[916] in which a female, on the advice of an old woman, inhaled for some affection or other 2·5 grms. of mercury poured on red-hot coals, and died in ten days with all the symptoms of mercurial poisoning.

The metal taken in bulk into the stomach has been considered non-poisonous, and, probably, when perfectly pure, it is so; we have, however, the case of a girl who swallowed 4¹⁄₂ ozs. by weight of the liquid metal, for the purpose of procuring abortion—this it did not effect; but, in a few days, she suffered from a trembling and shaking of the body and loss of muscular power. These symptoms continued for two months, but there was no salivation and no blue marks on the gums. This case is a rare one, and a pound or more has been taken without injury.

§ 838. Absorption of Mercury by the Skin.—Mercury in a finely divided form, rubbed into the skin, is absorbed, and all the effects of mercurialism result. This method of administering mercury for medicinal purposes has long been in use, but, when the inunction is excessive, death may occur. Thus, Leiblinger records a case in which three persons were found dead in bed; the day before they had rubbed into the body, for the purpose of curing the itch, a salve containing 270 grms. of mercury finely divided.

It is difficult to say in what proportion workers in mercury, such as water-gilders, &c., suffer. According to Hirt, not only do 1·5 to 2·1 per cent. of the workmen employed in smelting mercury ores suffer acutely, but as high a proportion as 8·7 per cent. are slightly affected.

§ 839. Symptoms of Poisoning by Mercury Vapour.—The symptoms of poisoning by mercury vapour, or by the finely divided metal, are the same as those which arise from the corrosive salts, with the exception of the local action. In mild cases there is pallor, languor, and sore mouth (from slightly inflamed gums), fœtid breath, and disorder of the digestive organs. If the action is more intense, there is an inflammation of the gums and, indeed, of the whole mouth, and salivation, which is sometimes so profuse that as much as two gallons of saliva have been secreted daily. The saliva is alkaline, has a bad odour, and its specific gravity in the early stages is increased, but ultimately becomes normal; the gums are raised into slight swellings, which gradually enlarge and coalesce. The teeth that are already carious, decay more rapidly; they become loose, and some may be shed; the inflammatory action may extend to the jaw, and necrosis of portions of the bone is no unusual occurrence. On recovery, the cheeks sometimes form adhesions with the gums, and cicatrices always mark the loss of substance which such an affection entails. With the stomatitis there are disturbances of the gastro-intestinal tract—nausea and vomiting, pain in the stomach, and diarrhœa alternating with constipation. Conjunctivitis is very common, both in man and animals, from exposure to mercury vapours. The further action of the metal is shown in its profound effects on the nervous system. The patient is changed in his disposition, he is excitable, nervous, or torpid; there are sleeplessness and bad dreams, at the same time headache, noises in the ears, giddiness, faintings, &c.

§ 840. Mercurial Tremor.—Mercurial tremor[917] may follow, or accompany the above state, or it may be the chief and most prominent effect. It specially affects the arms, partly withdrawing the muscles from the control of the will, so that a person affected with mercurial tremor is incapacitated for following any occupation, especially those requiring a delicate and steady touch. In cases seriously affected, the tremor spreads gradually to the feet and legs, and finally the whole body may be invaded. The patient is no longer master of his muscles—the muscular system is in anarchy, each muscle aimlessly contracting and relaxing independently of the rest—the movement of the legs becomes uncertain, the speech stuttering, the facial expressions are even distorted into grimaces, and the sufferer sinks into a piteous state of helplessness. The convulsive movements generally cease during sleep. The tremors are accompanied by interference with the functions of other organs: the respiration is weakened and difficult; dyspnœa, or an asthmatic condition, results; the pulse is small and slow; paresis, deepening into paralysis of the extremities, or of a group of muscles, follows; and, lastly, if the condition is not alleviated, the patient becomes much emaciated and sinks from exhaustion. Pregnant women are liable to abortion, and the living infants of women suffering from tremor have also exhibited tremor of the limbs.

In the case of the “mass poisoning” on board the “Triumph,” it has been mentioned that several of the sailors became consumptive, and the same effect has been noticed among all workers in the metal; it is now, indeed, an accepted fact that the cachexia induced by mercurialismus produces a weak habit of body specially liable to the tuberculous infection.

The course of the poisoning is generally more rapid when it has resulted from the taking of mercury internally as a medicine than when inhaled by workers in the metal, e.g., a patient suffering from mercurial tremor shown to the Medical Society by Mr. Spencer Watson in 1872, had resisted for seven years the influence of the fumes of mercury; and then succumbed, exhibiting the usual symptoms. Idiosyncrasy plays a considerable rôle; some persons (and especially those whose kidneys are diseased) bear small doses of mercury ill, and are readily salivated or affected; this is evidently due to imperfect elimination.

§ 841. Mercuric Methide, Hg(CH₃)₂.—This compound is obtained by the action of methyl iodide on sodium amalgam in the presence of acetic ether. It is a dense, stable liquid, of highly poisonous properties. In 1865, mercuric methide, in course of preparation in a London laboratory, caused two cases of very serious slow poisoning.[918] One was that of a German, aged 30, who was engaged in preparing this compound for three months, and during this time his sight and hearing became impaired; he was very weak, his gums were sore, and he was ultimately admitted into St. Bartholomew’s Hospital, February 3rd, 1865. His urine was found to be albuminous, and his mental faculties very torpid. On the 9th he became noisy, and had to be put under mechanical restraint. On the 10th he was semi-comatose, but there was no paralysis; his breath was very offensive, his pupils dilated; at intervals he raised himself and uttered incoherent howls. There was neither sensation nor motion in the left leg, which was extended rigidly; the knee and the foot were turned slightly inward. On the 14th he died insensible.

The only appearance of note seen at the autopsy was a congestion of the grey matter in the brain; the kidneys and liver were also congested, and there were ecchymoses in the kidneys.

The second case—a young man, aged 23, working in the same laboratory—was admitted into the hospital, March 28th, 1865. In the previous January he had been exposed to the vapour of mercuric methide for about a fortnight; during the illness of the other assistant he felt ill and weak, and complained of soreness of the gums and looseness of the teeth. He had also dimness of vision, pain and redness of the eyes, giddiness, nausea and vomiting, the ejected matters being greenish and watery. At the beginning of March his sight and taste became imperfect—all things tasted alike; his tongue was numb and his gums sore, he was also salivated slightly. A week before admission he lost his hearing, and first his hands and then his feet became numb; on admission his breath was very offensive, his pupils dilated; the sight impaired; he was very deaf, and his powers of speech, taste, and smell were deficient. There was anæsthesia of the body, and the movement of the limbs was sluggish and difficult. He continued in the hospital for nearly a month, with but little change. On April 24th, it was noticed that he was getting thinner and slightly jaundiced; he moved his arms aimlessly in an idiotic manner, and passed his urine involuntarily. On April 27th he was more restless, and even violent, shrieking out and making a loud, incoherent noise, or laughing foolishly; he passed his motions and urine beneath him. On July 7th he was in a similar state—perfectly idiotic. He died on April 7th, 1866, about a year and three months from his first exposure to the vapour; the immediate cause of death was pneumonia. The post-mortem appearances of the brain and membranes differed little from the normal state; the grey matter was pink, but otherwise healthy; there was a considerable amount of cerebro-spinal fluid; the arachnoid along the longitudinal fissure was thickened; the total weight of the brain with medulla was 41 ozs. The stomach was of enormous size; the pyramids of the kidneys were congested, as was also the small intestine; the lungs showed the usual signs of pneumonia.[919]

§ 842. Effects of the Corrosive Salts of Mercury.—The type of the corrosive salts is mercuric chloride, or corrosive sublimate—a compound which acts violently when administered, either externally or internally, in large doses.[920] If the poison has been swallowed, the symptoms come on almost immediately, and always within the first half hour; the whole duration also is rapid. In 36 cases collected by F. A. Falck, 11 died on the first or second day, and 11 on the fifth day; so that 61 per cent. died in five days—the remainder lived from six to twenty-six days. The shortest fatal case on record is one communicated to Dr. Taylor by Mr. Welch; in this instance the man died from an unknown quantity within half an hour.

In the very act of swallowing, a strong metallic taste and a painful sensation of constriction in the throat are experienced. There is a burning heat in the throat extending downwards to the stomach. All the mucous membranes with which the solution comes in contact are attacked, shrivelled, and whitened; so that, on looking into the mouth, the appearance has been described as similar to that produced by the recent application of silver nitrate. The local changes may be so intense as to cause œdema of the glottis, and death through asphyxia. In a few minutes violent pain is felt in the stomach; so much so, that the sufferer is drawn together, and is in a fainting condition; but there are rare cases in which pain has been absent. There are nausea and vomiting, the ejected matters being often streaked with blood; after the vomiting there is purging; here also the motions are frequently bloody.[921] The temperature of the body sinks, the respiration is difficult, and the pulse small, frequent, and irregular. The urine is generally scanty, and sometimes completely suppressed.[922] Sometimes there is profuse hæmorrhage from the bowel, stomach, or other mucous membrane, and such cases are accompanied by a considerable diminution of temperature. In a case recorded by Lœwy,[923] after a loss of blood by vomiting and diarrhœa, the temperature sank to 33·4°. The patient dies in a state of collapse, or insensibility, and death is often preceded by convulsions.

§ 843. Two remarkable cases of death from the external use of corrosive sublimate are recorded by Anderseck. An ointment, containing corrosive sublimate, was rubbed into the skin of two girls, servants, in order to cure the itch. The one, during the inunction, complained of a burning of the skin; the other also, a little while after, suffered in the same way. During the night the skin of each swelled, reddened, and became acutely painful. There were thirst and vomiting, but no diarrhœa, On the following day there was an eruption of blebs or little blisters. On the third day they had diarrhœa, tenesmus, fever, and diminution of the renal secretion; on the fourth day, fœtid breath, stomatitis, hyperæsthesia of the body, and a feeling of “pins and needles” in the hands and feet were noted. The first girl died in the middle of the fifth day, fully conscious; the other died on the sixth. So also Taylor[924] gives the case of a girl, aged 9, who died from the effects of an alcoholic solution of corrosive sublimate (strength, 80 grains to the oz.) applied to the scalp as a remedy for ringworm. The same author[925] further quotes the case of two brothers who died—the one on the fifth, the other on the eleventh day—from the effects of absorbing corrosive sublimate through the unbroken skin.

§ 844. The Nitrates of Mercury are poisons, but little (if at all) inferior in corrosive action to mercuric chloride. Death has resulted from both the external and internal use. Application of the nitrate as an escharotic to the os uteri, in one case,[926] produced all the symptoms of mercurial poisoning, but the woman recovered; in another case,[927] its use as a liniment caused death.

§ 845. When taken internally, the symptoms are scarcely different from those produced by corrosive sublimate. It seems an unlikely vehicle for criminal poisoning, yet, in the case of Reg. v. E. Smith (Leicester Summer Assizes, 1857), a girl was proved to have put a solution of nitrate of mercury in some chamomile tea, which had been prescribed for the prosecutrix. The nauseous taste prevented a fatal dose being taken; but the symptoms were serious.

§ 846. Mercuric Cyanide acts in a manner very similar to that of corrosive sublimate, 1·3 grm. (about 20 grains) in one case,[928] and in another[929] half the quantity, having destroyed life.

§ 847. White Precipitate (ammoniated mercury), as a poison, is weak. Out of fourteen cases collected by Taylor, two only proved fatal; one of these formed the subject of a trial for murder, Reg. v. Moore (Lewes Lent Assizes, 1860). The effects produced are vomiting, purging, &c., as in corrosive sublimate.[930] Other preparations of mercury, such as the red iodide, the persulphide, and even calomel,[931] have all a more or less intense poisonous action, and have caused serious symptoms and death.

§ 848. Treatment of Acute and Chronic Poisoning.—In acute poisoning, vomiting usually throws off some of the poison, if it has been swallowed; and the best treatment seems to be, to give copious albuminous drinks, such, for example, as the whites of eggs in water, milk, and the like. The vomiting may be encouraged by subcutaneous injections of apomorphine. The after-treatment should be directed to eliminating the poison, which is most safely effected by very copious drinks of distilled water (see “Appendix”).

The treatment of slow poisoning is mainly symptomatic; medicinal doses of zinc phosphide seem to have done good in mercurial tremors. Potassic iodide is also supposed to assist the elimination of mercury.

§ 849. Post-mortem Appearances.—The pathological effects seen after chronic poisoning are too various to be distinctive. In the museum of the Royal College of Surgeons there is (No. 2559) the portion of a colon derived from a lady aged 74.[932] This lady had been accustomed for forty-three years to take a grain of calomel every night; for many years she did not suffer in health, but ultimately she became emaciated and cachectic, with anasarca and albuminuria. The kidneys were found to be granular, and the mucous membrane of a great part of the intestine of a remarkable black colour, mottled with patches of a lighter hue, presenting somewhat the appearance of a toad’s back. From the portion of colon preserved mercury was readily obtained by means of Reinsch’s test. The black deposit is in the submucosa, and it is, without doubt, mercurial, and probably mercury sulphide. In acute poisoning (especially by the corrosive salts) the changes are great and striking. After rapid death from corrosive sublimate, the escharotic whitening of the mouth, throat, and gullet, already described, will be seen. The mucous membrane right throughout, from mouth to anus, is more or less affected and destroyed, according to the dose and concentration of the poison. The usual appearances in the stomach are those of intense congestion, with ecchymoses, and portions of it may be destroyed. Sometimes the coats are very much blackened; this is probably due to a coating of sulphide of mercury.

In St. George’s Hospital Museum (Ser. ix. 43, y. 337) there is a stomach, rather large, with thickened mucous coats, and having on the mucous surface a series of parallel black, or black-brown lines of deposit; it was derived from a patient who died from taking corrosive sublimate. With the severe changes mentioned, perforation is rare.[933] In the intestines there are found hyperæmia, extravasations, loosening of the mucous membrane, and other changes. The action is particularly intense about the cæcum and sigmoid flexure; in one case,[934] indeed, there was little inflammatory redness of the stomach or of the greater portion of the intestine, but the whole surface of the cæcum was of a deep black-red colour, and there were patches of sloughing in the coats. The kidneys are often swollen, congested, or inflamed; changes in the respiratory organs are not constantly seen, but in a majority of the cases there have been redness and swelling of the larynx, trachea, and bronchi, and sometimes hepatisation of smaller or larger portions of the lung.

In St. George’s Hospital Museum, there are (from a patient dying in the hospital) preparations which well illustrate what pathological changes may be expected in any case surviving for a few days. The patient was Francis L——, aged 45, admitted to the hospital, February 27, 1842. He took a quantity of corrosive sublimate spread on bread and butter, was immediately sick, and was unable to take as much as he had intended. The stomach-pump and other remedies were used. On the following day his mouth was sore, and on March 1st his vision was dim; his mouth was drawn over to the right side, and he lost power over the left eyelid, but he had no pain; he passed some blood from the bowel. On the 2nd he passed much blood, and was salivated; still no pain. On March 4, on the evening of the sixth day, he expired; he was drowsy during the last day, and passed watery evacuations.

Prep. 14a, Ser. ix., shows the pharynx, œsophagus, and tongue; there is ulceration of the tonsils, and fibrinous exudation on the gullet. The stomach (43b, 199) shows a large dark slough, three inches from the cardiac extremity; the margin surrounding the slough is thickened, ulcerated, and irregular in shape, the submucous tissue, to some extent, being also thickened; there is fibrine in the ileum, pharynx, and part of the larynx. The action extended to the whole intestine, the rectum in prep. 145a, 36, is seen to be thickened, and has numerous patches of effused fibrine.

It is a curious fact that the external application of corrosive sublimate causes inflammatory changes in the alimentary canal of nearly the same intensity as if the poison had been swallowed. Thus, in the case of the two girls mentioned ante (p. 647), there was found an intense inflammation of the stomach and intestines, the mucous tissues being scarlet-red, swollen, and with numerous extravasations.

§ 850. The effects of the nitrate of mercury are similar to the preceding; in the few cases which have been recorded, there has been intense redness, and inflammation of the stomach and intestines, with patches of ecchymosis. White precipitate, cyanide of mercury, mercuric iodide, and mercurous sulphide (turpeth-mineral) have all caused inflammation, more or less intense, of the intestinal tract.

§ 851. Elimination of Mercury.—The question of the channels by which mercury is eliminated is of the first importance. It would appear certain that it can exist in the body for some time in an inactive state, and then, from some change, be carried into the circulation and show its effects.[935] Voit considers that mercury combines with the albuminous bodies, separating upon their oxidation, and then becoming free and active.[936]

Ullmann[937] found most mercury in the following order:—Kidneys, liver, spleen, a small quantity in the stomach, no mercury in the small intestine, but some in the large intestine; small weighable quantities in the heart and skeletal muscles, also in the lungs; but no mercury, when the dose was small, in brain, the salivary glands, abdominal glands, thyroid glands, the bile, or the bones.

The main channel by which absorbed mercury passes out of the body is the kidneys, whilst mercurial compounds of small solubility are in great part excreted by the bowel. A. Bynssen,[938] after experimenting with mercuric chloride (giving ·015 to ·15 grm., with a little morphine hydrochlorate), came to the conclusion that it could be detected in the urine about two hours, and in the saliva about four hours, after its administration; he considered that the elimination was finished in twenty-four hours.

From the body of a hound that, in the course of thirty-one days, took 2·789 grms. of calomel (2·368 Hg) in eighty-seven doses, about 94 per cent. of the substance was recovered on analysis:—

Mercurous Sulphide. Grms.

In the fæces, 2·1175

„ urine, 0·0550

„ brain, heart, lungs, spleen, pancreas, kidneys, scrotum, and penis, 0·0090

„ liver, 0·0140

„ muscles, 0·0114

2·2069

This equals 1·9 of metallic mercury.[939] Thus, of the whole 2·2 grms. of mercuric sulphide separated, over 95 per cent. was obtained from the fæces.

This case is of considerable interest, for there are recorded in toxicological treatises a few cases of undoubted mercurial poisoning in which no poison had been detected, although there was ample evidence that it had been administered by the mouth. In such cases, it is probable that the whole length of the intestinal canal had not been examined, and the analysis failed from this cause. When (as not unfrequently happens) the mercurial poison has entered by the skin, it is evident that the most likely localities are the urine, the liver, and the kidneys.[940]

In a case related by Vidal,[941] the Liquor Bellostii (or solution of mercuric nitrate) was ordered by mistake instead of a liniment. Although externally applied, it caused salivation, profuse diarrhœa, and death in nine days. The whole of the intestinal tract was found inflamed with extravasations, and mercury detected in the liver.

In any case of external application, if death ensues directly from the poison, evidence of its presence will probably be found; but too much stress must not be laid upon the detection of mercury, for, as Dr. Taylor says, “Nothing is more common than to discover traces of mercury in the stomach, bowels, liver, kidneys, or other organs of a dead body.”[942]

§ 852. Tests for Mercury.—Mercury, in combination and in the solid form, is most readily detected by mixing the substance intimately with dry anhydrous sodic carbonate, transferring the mixture to a glass tube, sealed at one end, and applying heat. If mercury be present, a ring of minute globules condenses in the cool part of the tube. If the quantity of mercury is likely to be very minute, it is best to modify the process by using a subliming cell (p. 258), and thus obtain the sublimate on a circle of thin glass in a convenient form for microscopical examination. If there is any doubt whether the globules are those of mercury or not, this may be resolved by putting a fragment of iodine on the lower disc of the subliming cell, and then completing it by the disc which contains the sublimate (of course, the supposed mercurial surface must be undermost); on placing the cell in a warm, light place, after a time the scarlet iodide is formed, and the identification is complete. Similarly, a glass tube containing an ill-defined metallic ring of mercury can be sealed or corked up with a crystal of iodine, and, after a few hours, the yellow iodide, changing to scarlet, will become apparent. There are few (if any) tests of greater delicacy than this.

Mercury in solution can be withdrawn by acidulating the liquid, and then inserting either simply a piece of gold foil, gold wire, or bright copper foil; or else, by a galvanic arrangement, such as iron wire wound round a gold coin, or gold foil attached to a rod of zinc; or, lastly, by the aid of gold or copper electrodes in connection with a battery. By any of these methods, mercury is obtained in the metallic state, and the metal with its film can be placed in a subliming cell, and globules deposited and identified, as before described.

The Precipitating Reagents for mercury are numerous: a solution of stannous chloride, heated with a solution of mercury, or any combination, whether soluble or insoluble, reduces it to the metallic state.

Mercurous Salts in solution yield, with potash, soda, or lime, a black precipitate of mercurous oxide. Mercuric Salts, a bright yellow precipitate of mercuric oxide.

Mercurous Salts yield black precipitates, with sulphides of ammonium and hydrogen. Mercuric Salts give a similar reaction, but, with sulphuretted hydrogen, first a whitish precipitate, passing slowly through red to black.

Mercurous Salts, with solutions of the chlorides, give a white precipitate of calomel; the Mercuric Salts yield no precipitate under similar circumstances. Mercurous Salts, treated with iodide of potassium, give a green mercurous iodide; Mercuric, a scarlet.

§ 853. The Detection of Mercury in Organic Substances and Fluids.—Ludwig’s process, previously described, is found in practice the best. Fluids, such as urine, must be evaporated to dryness, and then treated with hydrochloric acid. Such organs as the liver are cut up and boiled in 20 per cent. HCl. Distinct evidence of mercury in the liver has been obtained on a piece of copper gauze, in a case where a child had been given 2 grains of calomel before death. “Four ounces of the liver were treated with hydrochloric acid and water, and a small piece of pure copper placed in the acid liquid while warm, and kept there for about forty-eight hours. It acquired a slight silvery lustre, and globules of mercury were obtained from it by sublimation.”

To detect the cyanide of mercury may require special treatment, and Vitali[943] recommends the following process:—The fluid is acidified with tartaric acid and neutralised by freshly precipitated CaCO₃; a slight excess of hydric sulphide is added, and the flask allowed to rest for twenty-four hours in the cold. Then a further quantity of SH₂ is added, and a current of hydrogen passed through the liquid; the effluent gas is first made to bubble through a solution of bismuth nitrate in dilute nitric acid (for the purpose of absorbing SH₂), and then through aqueous potash (to absorb HCl); in the first flask the analyst will separate and identify mercury sulphide, while in the last flask there will be potassic cyanide, which will respond to the usual tests.

In those cases where no special search is made for mercury, but an acid (hydrochloric) solution is treated with sulphuretted hydrogen, mercury is indicated by the presence of a black precipitate, which does not dissolve in warm nitric acid.

The further treatment of the black sulphide may be undertaken in two ways:—

(1) It is collected on a porcelain dish, with the addition of a little nitric acid, and evaporated to dryness in order to destroy organic matter. Hydrochloric and a few drops of nitric acid are next added; the action is aided by a gentle heat, the solution finally evaporated to dryness on the water-bath, and the residue taken up by warm distilled water. The solution is that of a persalt of mercury, and the mercury can be separated by electrolysis, or indicated by the tests already detailed.

(2) The other method, and the most satisfactory, is to mix the sulphide while moist with dry carbonate of soda, make it into a pellet which will easily enter a reducing or subliming tube, dry it carefully, and obtain a sublimate of metallic mercury.

A neat method of recognising mercury when deposited as a film on copper has been proposed by E. Brugnatelli:[944] the copper, after being washed, is transferred to a glass vessel, and a porcelain lid, on which a drop of gold chloride solution has been placed, adjusted over the dish. The whole is heated by a water-bath. The mercury vapour reduces the gold chloride, and gold is deposited as a bluish-violet stain; ¹⁄₁₀ mgrm. mercury may by this test be identified.

Of special methods for the separation and detection of mercury, Ludwig’s[945] is, without a doubt, the best when organic matters have to be dealt with; the finely divided solid substances are boiled for some hours with hydrochloric acid, strength 20 per cent.; then the liquid is cooled to 60°, and potassic chlorate added in half gramme quantities until the dark liquid becomes clear; the liquid is cooled and filtered, and the substances on the filter washed with water. To the filtrate 5 grms. of zinc dust are added, and the liquid is violently shaken from time to time; a second portion is afterwards added, and also vigorously shaken. After some hours the clear liquid is separated from the zinc and the zinc washed, first with water, then with a little soda solution, and finally, again with water. The zinc is now collected on a glass-wool filter, treated with absolute alcohol to remove water, and dried by suction in a stream of air. The zinc is put into a combustion-tube, the tube being drawn out into a thin capillary extremity, and a combustion made, the mercury collecting at the capillary part. It is a necessary refinement, should the zinc be contaminated with a trace of organic matter, to pack the combustion-tube as follows:—First, the zinc dust on which any mercury present has been deposited, then a plug of asbestos; next, some cupric oxide; and lastly, some pure zinc dust. Bondzynski[946] prefers to use copper rather than zinc; for he says that zinc so frequently contains cadmium, which latter metal also gives a mirror, so that, unless the mercury is afterwards identified by turning it into an iodide, error may be caused.

§ 854. Estimation of Mercury.—All pharmaceutical substances containing mercury, as well as the sulphide prepared in the wet way, and minerals, are best dealt with by obtaining and weighing the metal in the solid state. The assay is very simple and easy when carried out on the method that was first, perhaps, proposed by Domeyko. A glass tube (which should not be too thin), closed at one end, is bent, as shown in the figure, the diameter should be about three lines, the length from 7 to 8 inches, the shorter arm not exceeding 2 inches. The powdered substance is mixed with two or three times its weight of litharge, and introduced into the tube at a. The portion of the tube containing the mercury is at first heated gently, but finally brought to a temperature sufficient to fuse the substance and soften the glass. The mercury collects in an annular film at b in the cooler limb, and may now, with a little management of the lamp, be concentrated in a well-defined ring; the portion of the tube containing this ring is cut off, weighed, then cleansed from mercury, and reweighed. Many of the pharmaceutical preparations do not require litharge, which is specially adapted for ores, and heating with sodic carbonate (in great excess) will suffice. Mercury mixed with organic matter must be first separated as described, by copper or gold, the silvered foil rolled up, dried, introduced into the bent tube, and simply heated without admixture with any substance; the weight may be obtained either by weighing the foil before and after the operation, or as above.

§ 855. Volumetric Processes for the Estimation of Mercury.—When a great number of mercurial preparations are to be examined, a volumetric process is extremely convenient. There are several of these processes, some adapted more particularly for mercuric, and others for mercurous compounds. For mercuric, the method of Personne[947] is the best. The conversion of the various forms of mercury into corrosive sublimate may be effected by evaporation with aqua regia, care being taken that the bath shall not be at a boiling temperature, or there will be a slight loss.

Personne prefers to heat with caustic soda or potash, and then pass chlorine gas into the mixture; the excess of chlorine is expelled by boiling, mercuric chloride in presence of an alkaline chloride not being volatilised at 100°. The standard solutions required for this process are:—

(1) 33·2 grms. of potassic iodide in 1 litre of water, 1 c.c. = 0·01 grm. Hg, or 0·01355 grm. HgCl₂.

(2) A solution of mercuric chloride containing 13·55 grms. to the litre, 1 c.c. = 0·1 grm. Hg.

The process is founded on the fact that, if a solution of mercuric chloride be added to one of potassic iodide, in the proportion of one of the former to four of the latter, mercuric iodide is formed, and immediately dissolved, until the balance is overstepped, when the red colour is developed; the final reaction is very sharp, and with solutions properly made is very accurate. The mercuric solution must always be added to the alkaline iodide; a reversal of the process does not answer. It therefore follows that the solution to be tested must be made up to a definite bulk, and added to a known quantity of the potassic iodide until the red colour appears.

Mercurous Salts may be titrated with great accuracy by a decinormal solution of sodic chloride. This is added to the cold solution in very slight excess, the calomel filtered off, the filtrate neutralised by pure carbonate of soda, and the amount of sodic chloride still unused found by titration with nitrate of silver, the end reaction being indicated by chromate of potash. Several other volumetric processes are fully described in works treating upon this branch of analysis.

III.—PRECIPITATED BY HYDRIC SULPHIDE FROM A NEUTRAL SOLUTION. Zinc—Nickel—Cobalt.

1. ZINC.

§ 856. Zinc—At. wt., 65; specific gravity, 6·8 to 7·1; fusing-point, 412° (773° F.)—is a hard, bluish-white, brittle metal, with a crystalline fracture. Between 100° and 150° it becomes ductile, and may be easily wrought, but at a little higher temperature it again becomes brittle, and at a bright red heat it fuses, and then volatilises, the fumes taking fire when exposed to the air. In analysis, zinc occurs either as a metallic deposit on a platinum foil or dish, or as a brittle bead, obtained by reducing a zinc compound with soda on charcoal.

The salts of zinc to be briefly described here are the carbonate, the oxide, and the sulphide,—all of which are likely to occur in the separation and estimation of zinc, and the sulphate and chloride,—salts more especially found in commerce, and causing accidents from time to time.

§ 857. Carbonate of Zinc, in the native form of calamine, contains, as is well known, 64·8 per cent. of oxide of zinc; but the carbonate obtained in the course of an analysis by precipitating the neutral hot solution of a soluble salt of zinc by carbonate of potash or soda, is carbonate of zinc plus a variable quantity of hydrated oxide of zinc. Unless the precipitation takes place at a boiling temperature, the carbonic anhydride retains a portion of the oxide of zinc in solution. By ignition of the carbonate, oxide of zinc results.

§ 858. Oxide of Zinc (ZnO = 81; specific gravity, 5·612; Zn, 80·24, O, 19·76) is a white powder when cool, yellow when hot. If mixed with sufficient powdered sulphur, and ignited in a stream of hydrogen, the sulphide is produced; if ignited in the pure state in a rapid stream of hydrogen gas, metallic zinc is obtained; but, if it is only a feeble current, the oxide of zinc becomes crystalline, a portion only being reduced.

§ 859. Sulphide of Zinc (ZnS = 97; specific gravity, 4·1; Zn, 67·01, S, 32·99).—The sulphide obtained by treating a neutral solution of a soluble salt of zinc by hydric sulphide is hydrated sulphide, insoluble in water, caustic alkalies, and alkaline sulphides, but dissolving completely in nitric or in hydrochloric acid. When dry, it is a white powder, and if ignited contains some oxide of zinc. The anhydrous sulphide is produced by mixing the precipitated sulphide with sulphur, and igniting in a crucible in a stream of hydrogen gas.

Pharmaceutical Preparations.—The officinal compounds of zinc used in medicine are the acetate, carbonate, chloride, oxide, sulphate, sulphocarbolate, and valerianate.

Sulphate of Zinc (ZnSO₄7H₂O 161 + 126; specific gravity, crystals, 1·931).—This salt is officinal in all the pharmacopœias, is used in calico-printing, and is commonly known as white vitriol. By varying the temperature at which the crystals are allowed to be formed, it may be obtained with 6, 5, 2, or 1 atoms of water. The commercial sulphate is in crystals exactly similar to those of Epsom salts; it is slightly efflorescent, and gives the reactions of zinc and sulphuric acid.

§ 860. Chloride of Zinc is obtained by dissolving zinc in hydrochloric acid, or by direct union of zinc and chlorine. Chloride of zinc is the only constituent in the well-known “Burnett’s disinfectant fluid.” A solution of chloride of zinc may be heated until it becomes water-free; when this takes place it still remains fluid, and makes a convenient bath, for warmth may be applied to it above 370° without its emitting fumes to inconvenience; at a red heat it distils. A concentrated solution of zinco-ammonic chloride (2H₄NClZnCl₂) is used for the purpose of removing the film of oxide from various metals preparatory to soldering.

§ 861. Zinc in the Arts.—The use of zinc as a metal in sheeting cisterns, articles for domestic use, alloys, &c., is well known; oxide of zinc enters largely into the composition of india-rubber. Sulphide of zinc has been employed as a substitute for white lead, and may possibly supersede it. Zinc white is further employed as a pigment, and, mixed with albumen, is an agent in calico-printing; it is also used in the decoloration of glass, in the polishing of optical glasses, and in the manufacture of artificial meerschaum pipes.[948]

Chromate of Zinc (ZnCrO₄) is used in calico-printing, and there is also in commerce a basic chromate known as zinc yellow. Zinc green, or Rinman’s green, is a beautiful innocuous colour, formed by igniting a mixture of dry zincic and cobaltous carbonates.

The use of zinc vessels in the preparation of foods may occasionally bring the metal under the notice of the analyst. When exposed to a moist atmosphere, zinc becomes covered with a thin film of oxide, perfectly insoluble in ordinary water; but, if the water should be charged with common salt, a considerable quantity may be dissolved. It may generally be laid down as a rule that the solvent power of water on zinc has a direct relation to the chlorides present, whilst carbonate of lime greatly diminishes this solubility.[949]

Milk may become contaminated by zinc; for, it is a matter of common knowledge, that milk contained in zinc vessels does not readily turn sour. This may be explained by the zinc oxide combining with the lactic acid, and forming the sparingly soluble lactate of zinc 2(C₃H₅O₃)Zn + 3H₂O, thus withdrawing the lactic acid as fast as it is formed, preventing the coagulation of the casein. With regard to this important practical subject, MM. Payne and Chevallier made several experiments on the action of brandy, wine, vinegar, olive oil, soup, milk, &c., and proved that zinc is acted on by all these, and especially by alcoholic, acetic, and saline liquids. M. Schaufféle has repeated these experiments, and determined the amount of zinc dissolved in fifteen days by different liquids from a galvanised iron as well as a zinc vessel.

The amount found was as follows:—

The liquid from the zinc vessel, grms. per litre. The liquid from the galvanised iron vessel, grms. per litre.

Brandy, 0 ·95 0 ·70

Wine, 3 ·95 4 ·10

Orange-flower water, 0 ·50 0 ·75

Vinegar, 31 ·75 60 ·75

Fatty soup, 0 ·46 1 ·00

Weak soup, 0 ·86 1 ·76

Milk, 5 ·13 7 ·00

Salt water, 1 ·75 0 ·40

Seltzer water, 0 ·35 0 ·30

Distilled water, traces. traces.

Ordinary water, traces. traces.

Olive oil, none. none.

§ 862. Effects of Zinc, as shown by Experiments on Animals.—Harnack, in experiments with sodium-zinc oxide pyrophosphate, has shown that the essential action of zinc salts is to paralyse the muscles of the body and the heart, and, by thus affecting the circulation and respiration, to cause death; these main results have been fully confirmed by Blake, Letheby, and C. Ph. Falck. For rabbits the lethal dose is ·08 to ·09 grm. of zinc oxide, or about ·04 per kilogrm. The temperature during acute poisoning sinks notably—according to F. A. Falck’s researches on rabbits, from about 7·3° to 13·0°. Zinc is eliminated mainly by the urine, and has been recognised in that fluid four to five days after the last dose. It has also been separated in small quantity from the milk and the bile.

§ 863. Effects of Zinc Compounds on Man—(a) Zinc Oxide.—The poisonous action of zinc oxide is so weak that it is almost doubtful whether it should be considered a poison. Dr. Marcett has given a pound (453·6 grms.) during a month in divided doses without injury to a patient afflicted with epilepsy; and the workmen in zinc manufactories cover themselves from head to foot with the dust without very apparent bad effects. It is not, however, always innocuous, for Popoff has recorded it as the cause of headache, pain in the head, cramps in the calves of the legs, nausea, vomiting, and diarrhœa; and he also obtained zinc from the urine of those suffering in this manner.[950] Again, a pharmacy student[951] filled a laboratory with oxide of zinc vapour, and suffered from well-marked and even serious poisonous symptoms, consisting of pain in the head, vomiting, and a short fever. It must be remembered that, as the ordinary zinc of commerce is seldom free from arsenic, and some samples contain gallium, the presence of these metals may possibly have a part in the production of the symptoms described.

§ 864. (b) Sulphate of Zinc.—Sulphate of zinc has been very frequently taken by accident or design, but death from it is rare. The infrequency of fatal result is due, not to any inactivity of the salt, but rather to its being almost always expelled by vomiting, which is so constant and regular an effect, that in doses of 1·3 grm. (20 grains), sulphate of zinc is often relied upon in poisoning from other substances to quickly expel the contents of the stomach. In a case reported by Dr. Gibb, an adult female swallowed 4·33 grms. (67 grains), but no vomiting occurred, and it had to be induced by other emetics; this case is unique. It is difficult to say what would be a fatal dose of zinc sulphate, but the serious symptoms caused by 28 grms. (1 oz.) in the case of a groom in the service of Dr. Mackenzie, leads to the view that, although not fatal in that particular instance, it might be in others. The man took it in mistake for Epsom salts: a few minutes after he was violently sick and purged, and was excessively prostrated, so that he had to be carried to his home; the following day he had cramps in the legs, and felt weak, but was otherwise well.

In a criminal case related by Tardieu and Roussin, a large dose of zinc sulphate, put into soup, caused the death of an adult woman of sixty years of age in about thirty hours.[952] The symptoms were violent purging and vomiting, leading to collapse. From half of the soup a quantity of zinc oxide, equal to 1·6 grm. of zinc sulphate, was separated. Zinc was also found in the stomach, liver, intestines, and spleen—(see also a case of criminal poisoning recorded by Chevallier).[953]

§ 865. (c) Zinc Chloride.—Chloride of zinc is a powerful poison, which may kill by its primary or secondary effects; its local action as a caustic is mainly to be ascribed to its intense affinity for water, dehydrating any tissue with which it comes in contact. The common use of disinfecting fluids containing zinc chloride, such as Burnett’s fluid, leads to more accidents in England than in any other European country. Of twenty-six cases of poisoning by this agent, twenty-four occurred in England, and only two on the Continent. Death may follow the external use of zinc chloride. Some years ago, a quack at Barnstaple, Devon, applied zinc chloride to a cancerous breast; the woman died with all the general symptoms of poisoning by zinc, and that metal was found in the liver and other organs.

The symptoms observed in fatal cases of chloride of zinc poisoning are—immediate pain in the throat, and burning of the lips, tongue, &c. There is difficulty in swallowing, an increase in the secretion of saliva, vomiting of bloody matters, diarrhœa, collapse, coma, and death. In some cases life has been prolonged for days; but, on the other hand, death has been known to occur in a few hours. In those cases in which either recovery has taken place, or in which death is delayed, nervous symptoms rarely fail to make their appearance. In a case recorded by Dr. R. Hassall, 3 ounces of Burnett’s fluid were swallowed. The usual symptoms of intense gastro-intestinal irritation ensued, but there was no purging until the third day; after the lapse of a fortnight, a train of nervous symptoms set in, indicated by a complete perversion of taste and smell. In other cases, aphonia, tetanic affections of groups of muscles, with great muscular weakness and impairment of sight, have been noticed. Very large doses of zinc chloride have been recovered from, e.g., a man had taken a solution equivalent to about 13 grms. (200 grains) of the solid chloride. Vomiting came on immediately, and there was collapse, but he recovered in sixteen days. On the other hand, ·38 grm. (6 grains) has destroyed life after several weeks’ illness.

§ 866. Post-mortem Appearances.—In poisoning by sulphate of zinc, the appearances usually seen are inflammation, more or less intense, of the mucous membrane of the stomach and bowels. In the museums of the London hospitals, I could only find (1882) a single specimen preserved illustrating the effects of this poison. This preparation is in St. George’s Hospital Museum, and shows (ser. ix. 43 and 198) the stomach of a man who died from zinc sulphate, and whose case is reported in the Lancet, 1859. The mucous membrane is wrinkled all over like a piece of tripe; when recent it was vascular and indurated, but uniformly of a dirty grey colour; the lining membrane of the small intestine is very vascular, and in the duodenum and upper part of the jejunum the colour is similar to that of the stomach, but in a less marked degree; the stomach and intestines are contracted.

The pathological appearances after chloride of zinc vary according to the period at which death takes place. When it has occurred within a few hours, the lining membrane of the mouth and gullet shows a marked change in texture, being white and opaque, the stomach hard and leathery, or much corrugated or ulcerated. In cases in which life has been prolonged, contractions of the gullet and stomach may occur very similar to those caused by the mineral acids, and with a similar train of symptoms. In a case which occurred under Dr. Markham’s[954] observation, a person died ten weeks after taking the fatal dose, the first symptoms subsiding in a few days, and the secondary set of symptoms not commencing for three weeks. They then consisted mainly of vomiting, until the patient sank from exhaustion. The stomach was constricted at the pyloric end, so that it would scarcely admit a quill.

In Guy’s Hospital there is a good preparation, 1799³⁵, from the case of S. R., aged 22; she took a tablespoonful of Burnett’s fluid, and died in about fourteen weeks. There were at first violent vomiting and purging, but she suffered little pain, and in a day or two recovered sufficiently to move about the house; but the vomiting after food continued, everything being ejected about five minutes after swallowing. Before death she suffered from pneumonia. The stomach is seen to be much contracted—5 inches in length; it is ulcerated both near the pylorus and near the gullet; at the latter part there is a pouch-like portion of the mucous membrane of the stomach adherent to the spleen, which communicates by a perforation with an abscess formed and bounded by the stomach, diaphragm, and spleen; it contained 3 ozs. of dirty-looking pus. At the pylorus, in the centre, there is a second perforation, but extravasation of the contents is prevented by the adherent omentum and transverse colon. The muscular coats are thickened.

§ 867. Detection of Zinc in Organic Liquids or Solids.—In cases where the poison has been expelled from the stomach by vomiting, the muscles and bones would appear to be the best tissues to examine chemically; for Matzkewitsch investigated very carefully a dog poisoned by 100 parts of zinc, subcutaneously injected in the form of acetate, and found it distributed over the several organs of the body in the following ratios:—Muscles 60·5, bones 24·41, stomach and intestines 4·63, skin 3·70, place of injection 2·19, liver 1·75, lungs and heart 1·68, kidneys, bladder, and urine 1·14.

The only certain method of detection is to produce the sulphide of zinc, best effected by saturating a neutral or feebly acid liquid with hydric sulphide. If an organic liquid, which can be easily filtered, is operated upon, it may be strongly acidulated with acetic acid, and at once treated with hydric sulphide. If, however, zinc is sought for as a part of a systematic examination (as will most likely be the case), the solution will have been treated with hydrochloric acid, and already tested for arsenic, antimony, lead, &c., and filtered from any precipitate. In such a case the hydrochloric acid must first be replaced by acetic, which is effected by adding a slight excess of sodic acetate; the right quantity of the latter is easily known, if the hydrochloric acid originally added was carefully measured, and its specific gravity ascertained; 3·72 of crystallised sodic acetate saturating one of HCl. Lastly, should the distillation process, given at p. 49, have been adopted, the contents of the retort will only require to be treated with water, filtered, and saturated with sulphuretted hydrogen. In any of the above cases, should a white, dirty white or lightish-coloured precipitate (which is not sulphur) be thrown down, zinc may be suspected; it will, however, be absolutely necessary to identify the sulphide, for there are many sources of error. The most satisfactory of all identifications is the production of Rinman’s green. The supposed sulphide is dissolved off the filter with hot nitric acid, a drop or more (according to the quantity of the original precipitate) of solution of cobalt nitrate added, the solution precipitated with carbonate of soda and boiled, to expel all carbonic anhydride; the precipitate is then collected on a filter, washed, dried, and ignited in a platinum dish. If zinc be present in so small a proportion as 1·100,000 part, the mass will be permanently green.

§ 868. Other methods of procedure are as follows:—The supposed zinc sulphide (after being well washed) is collected in a porcelain dish, and dissolved in a few drops of sulphuric acid, filtered, nitric acid added, evaporated to dryness, and heated to destroy all organic matter. When cool, the mass is treated with water acidulated by sulphuric acid, and again filtered. The solution may contain iron as well as zinc, and if the former (on testing a drop with ferrocyanide of potash) appears in any quantity, it must be separated by the addition of ammonia in excess to the ammoniacal filtrate; sodic carbonate is added in excess, the liquid well boiled, and the precipitate collected on a filter and washed. The carbonate of zinc thus obtained is converted into zinc oxide by ignition, and weighed. If oxide of zinc, it will be yellow when hot, white when cold: it will dissolve in acetic acid; give a white precipitate with sulphuretted hydrogen; and, finally, if heated on charcoal in the oxidising flame, and moistened with cobalt nitrate solution, a green colour will result. Zinc may also be separated from liquids by electrolysis. The simplest way is to place the fluid under examination in a platinum dish of sufficient size, acidify, and insert a piece of magnesium tape. The metallic film so obtained may be dissolved by hydrochloric acid, and the usual tests applied.

2. NICKEL—COBALT.

§ 869. The salts of nickel and cobalt have at present no toxicological importance, although, from the experiments of Anderson Stuart,[955] both may be classed as poisonous. The experiments of Gmelin had, prior to Stuart’s researches, shown that nickel sulphate introduced into the stomach acted as an irritant poison, and, if introduced into the blood, caused death by cardiac paralysis. Anderson Stuart, desiring to avoid all local irritant action, dissolved nickel carbonate in acid citrate of soda by the aid of a gentle heat; he then evaporated the solution, and obtained a glass which, if too alkaline, was neutralised by citric acid, until its reaction approximated to the feeble alkalinity of the blood; the cobalt salt was produced in the same way. The animals experimented on were frogs, fish, pigeons, rats, guinea-pigs, rabbits, cats, and dogs—in all 200. The lethal dose of nickelous oxide, when subcutaneously injected in the soluble compound described, was found to be as follows:—frogs, ·08 grm. per kilogram; pigeons, ·06; guinea-pigs, ·030; rats, ·025; cats, ·01; rabbits, ·009; and dogs, ·007. The cobaltous oxide was found to be much less active, requiring the above doses to be increased about two-thirds. In other respects, its physiological action seems to be very similar to that of nickelous oxide.

§ 870. Symptoms—Frogs.—A large dose injected into the dorsal lymph sac of the frog causes the following symptoms:—The colour of the skin all over the body becomes darker and more uniform, and not infrequently a white froth is abundantly poured over the integument. In an interval of about twenty minutes the frog sits quietly, the eyes retracted and shut; if molested, it moves clumsily. When quiet, the fore limbs are weak, and the hind legs drawn up very peculiarly, the thighs being jammed up so against the body, that they come to lie on the dorsal aspect of the sides of the frog, and the legs are so much flexed that the feet lie on the animal’s back, quite internal to the plane of the thighs. Soon fibrillary twitchings are observed in the muscles of the abdominal wall, then feeble twitchings of the fingers, and muscles of the fore limbs generally; lastly, the toes are seen to twitch, and then the muscles of the hind limbs—this order is nearly always observed; now spasmodic gaping and incoördinate movements are seen, and the general aspect is not unlike the symptoms caused by picrotoxin. After this, tetanus sets in, and the symptoms then resemble those of strychnine; the next stage is stupefaction and voluntary motor paresis; the respiratory movements become feeble, and the paresis passes into paralysis. The heart beats more and more slowly and feebly, and death gradually and imperceptibly supervenes. The post-mortem appearances are well marked, i.e., rigor mortis, slight congestion of the alimentary tract, the heart with the auricle much dilated and filled with dark blood, the ventricle mostly small, pale, and semi-contracted. For some time after death, the nerve trunks and muscles react to the induction current.

Pigeons.—In experiments on pigeons the symptoms were those of dulness and stupor, jerkings of different sets of muscles, and then death quietly.

Guinea-pigs.—In guinea-pigs there were dulness and stupefaction, with some weakness of the hind limbs.

Rats.—The symptoms in rats were almost entirely nervous; they became drowsy and apathetic, and there was paralysis of the hind legs.

Rabbits.—In rabbits, also, the symptoms were mainly those caused by an affection of the nervous system. There was paralysis, which affected either the hind legs only, or all four limbs. The cervical muscles became so weak that the animal was unable to hold its head up. Diarrhœa occurred and persisted until death. If the dose is not large enough to kill rapidly, the reflex irritability is decidedly increased, so that the slightest excitation may cause the animal to cower and tremble all over. Now appear twitchings and contractions of single groups of muscles, and this excitement becomes general. The respirations also become slower and more difficult, and sometimes there is well-marked dilatation of the vessels of the ears and fundi oculi. Convulsions close the scene.

§ 871. Circulation.—The effect of the salt on the frog’s heart was also studied in detail. It seems that, under the influence of a soluble salt of nickel, the heart beats more and more slowly, it becomes smaller and paler, and does not contract evenly throughout the whole extent of the ventricle; but the rhythm of the ventricular and auricular contractions is never lost.

It is probable that there is a vaso-motor paralysis of the abdominal vessels; the blood-pressure falls, and the heart is not stimulated by the blood itself as in its normal state. In support of this view, it is found that, by either pressing on the abdomen or simply inverting the frog, the heart swells up, fills with blood, and for a time beats well.

Nervous System.—The toxic action is referable to the central nervous system, and not to that of peripheral motor nerve-endings or motor nerve-fibres. It is probable that both nickel and cobalt paralyse to some extent the cerebrum. The action on the nerve-centres is similar to that of platinum or barium, and quite different from that of iron.

§ 872. Action on Striped Muscle.—Neither nickel nor cobalt has any effect on striped muscle. In this they both differ from arsenic, antimony, mercury, lead, and iron—all of which, in large doses, diminish the work which healthy muscle is capable of performing.

§ 873. Separation of Nickel or Cobalt from the Organic Matters or Tissues.—It is very necessary, if any case of poisoning should occur by either or both of these metals, to destroy completely the organic matters by the process already detailed on p. 51. Both nickel and cobalt are thrown down, if in the form of acetate, from a neutral solution by sulphuretted hydrogen; but the precipitation does not take place in the presence of free mineral acid; hence, in the routine process of analysis, sulphuretted hydrogen is passed into the acid liquid, and any precipitate filtered off. The liquid is now made almost neutral by potassic carbonate, and then potassic acetate added, and a current of sulphuretted hydrogen passed through it. The sulphides of cobalt and nickel, if both are present, will be thrown down; under the same circumstances zinc, if present, would also be precipitated. Cobalt is separated from zinc by dissolving the mixed sulphides in nitric acid, precipitating the carbonates of zinc and cobalt by potassic carbonate, collecting the carbonates, and, after washing, igniting them gently in a bulb tube, in a current of dry hydrochloric acid; volatile zinc chloride is formed and distils over, leaving cobalt chloride.

§ 874. To estimate cobalt, sulphide of cobalt may be dissolved in nitric acid, and then precipitated by pure potash; the precipitate washed, dried, ignited, and weighed; 100 parts of cobaltous oxide (Co₃O₄) equals 73·44 of metallic cobalt. Cobalt is separated from nickel by a method essentially founded on one proposed by Liebig. The nitric acid solution of nickel and cobalt (which must be free from all other metals, save potassium or sodium) is nearly neutralised by potassic carbonate, and mixed with an excess of hydrocyanic acid, and then with pure caustic potash. The mixture is left exposed to the air in a shallow dish for some hours, a tripotassic cobalticyanide (K₃CoCy₆) and a nickelo-potassic cyanide (2KCy, NiCy₄) are in this way produced. If this solution is now boiled with a slight excess of mercuric nitrate, hydrated nickelous oxide is precipitated, but potassic cobalticyanide remains in solution, and may be filtered off. On carefully neutralising the alkaline filtrate with nitric acid, and adding a solution of mercurous nitrate, the cobalt may then be precipitated as a mercurous cobalticyanide, which may be collected, washed, dried, decomposed by ignition, and weighed as cobaltous oxide. After obtaining both nickel and cobalt oxides, or either of them, they may be easily identified by the blowpipe. The oxide of nickel gives, in the oxidising flame with borax, a yellowish-red glass, becoming paler as it cools; the addition of a potassium salt colours the bead blue. In the reducing flame the metal is reduced, and can be seen as little greyish particles disseminated through the bead. Cobalt gives an intense blue colour to a bead of borax in the oxidising flame.

IV.—PRECIPITATED BY AMMONIUM SULPHIDE. Iron—Chromium—Thallium—Aluminium—Uranium.

1. IRON.

§ 875. It was Orfila’s opinion that all the salts of iron were poisonous, if given in sufficient doses; but such salts as the carbonate, the phosphate, and a few others, possessing no local action, may be given in such very large doses, without causing disturbance to the health, that the statement must only be taken as applying to the more soluble iron compounds. The two preparations of iron which have any forensic importance are the perchloride and the sulphate.

§ 876. Ferric Chloride (Fe₂Cl₆ = 325).—Anhydrous ferric chloride will only be met with in the laboratory. As a product of passing dry chlorine over red-hot iron, it sublimes in brown scales, is very deliquescent, and hisses when thrown into water. There are two very definite hydrates—one with 6 atoms of water, forming large, red, deliquescent crystals; and another with 12 of water, less deliquescent, and crystallising in orange stellate groups.

The pharmaceutical preparations in common use are:—

Stronger Solution of Perchloride of Iron (Liquor Ferri Perchloridi Fortior).—An orange-brown liquid of specific gravity 1·42, and containing about 58 per cent. of ferric chloride.

Tincture of Perchloride of Iron (Tinctura Ferri Perchloridi), made by diluting 1 part of the strong solution with 1 volume of rectified spirit, and adding distilled water to measure 4.

Solution of Perchloride of Iron (Liquor Ferri Perchloridi).—Simply 5 volumes of the strong solution made up to 20 by the addition of water; hence, of the same strength as the tincture.

§ 877. Effects of Ferric Chloride on Animals.—A very elaborate series of researches on rabbits, dogs, and cats was undertaken a few years ago by MM. Bérenger-Féraud and Porte[956] to elucidate the general symptoms and effects produced by ferric chloride under varying conditions. First, a series of experiments showed that, when ferric chloride solution was enclosed in gelatine capsules and given with the food of the animal, it produced either no symptoms or but trifling inconvenience, even when the dose exceeded 1 grm. per kilogrm.; anhydrous ferric chloride and the ferric chloride solution were directly injected into the stomach, yet, when food was present, death did not occur, and the effects soon subsided. In animals which were fasting, quantities of the solution equal to ·5 grm. per kilogrm. and above caused death in from one hour to sixteen hours, the action being much accelerated by the addition of alcohol—as, for example, in the case of the tincture: the symptoms were mainly vomiting and diarrhœa, sometimes the vomiting was absent. In a few cases the posterior extremities were paralysed, and the pupils dilated: the urine was scanty or quite suppressed; death was preceded by convulsions.

§ 878. Effects on Man.—Perchloride of iron in the form of tincture has been popularly used in England, from its supposed abortive property, and is sold under the name of “steel drops.” It has been frequently taken by mistake for other dark liquids; and there is at least one case on record in which it was proved to have been used for the purpose of murder. The latter case[957] is peculiarly interesting from its great rarity; it occurred in Martinique in 1874-1876, no less than four persons being poisoned at different dates. All four were presumed to have had immoral relations with a certain widow X——, and to have been poisoned by her son. In three of the four cases, viz., Char——, Duf——, and Lab——, the cause of death seems pretty clear; but the fourth, Ab——, a case of strong suspicion, was not sufficiently investigated. All three took the fatal dose in the evening, between eight and nine o’clock—Lab—— the 27th of December 1874, Duf—— the 22nd of February 1876, and Char—— on the 14th of May 1876. They had all passed the day in tippling, and they all had eaten nothing from mid-day, so that the stomach would, in none of the three, contain any solid matters. The chloride was given to them in a glass of “punch,” and there was strong evidence to show that the son of the widow X—— administered it. Char—— died after about thirteen hours’ illness, Duf—— and Lab—— after sixty-five hours’ illness; Ab—— lived from three to four days. With Char—— the symptoms were very pronounced in an hour, and consisted essentially of violent colicky pain in the abdomen and diarrhœa, but there was no vomiting; Duf—— had also great pain in the abdomen and suppression of the urine. Lab—— had most violent abdominal pains; he was constipated, and the urinary secretion was arrested; there was besides painful tenesmus. According to the experiments of Bérenger-Féraud and Porte,[958] the perchloride in the above cases was taken under conditions peculiarly favourable for the development of its toxic action, viz., on an empty stomach and mixed with alcohol.

There have been several cases of recovery from large doses of the tincture, e.g., that of an old man, aged 72, who had swallowed 85 c.c. (3 ozs.) of the tincture; the tongue swelled, there were croupy respiration and feeble pulse, but he made a good recovery. In other cases,[959] 28·3 c.c. (an ounce) and more have caused vomiting and irritation of the urinary organs. The perchloride is not unfrequently used to arrest hæmorrhage as a topical application to the uterine cavity—a practice not free from danger, for it has before now induced violent inflammation and death from peritonitis.

§ 879. Elimination of Iron Chloride.—Most of the iron is excreted in the form of sulphide by the fæces, and colours them of a black hue; a smaller portion is excreted by the urine.

§ 880. Post-mortem Appearances.—In the experiments on animals already referred to, the general changes noted were dryness, pallor, and parchment-like appearance of the cavity of the mouth, the mucous membrane being blackened by the contact of the liquid. The gullet was pale and dry, not unfrequently covered with a blackish layer. The mucous membrane of the stomach was generally healthy throughout; but, if the dose was large and very concentrated, there might be one or more hyperæmic spots; otherwise, this did not occur. The internal surface of the intestines, similarly, showed no inflammation, but was covered with brownish coating which darkened on exposure to the air. The liver, in all the experiments, was large and gorged with black and fluid blood; there were ecchymoses in the lungs and venous congestion. The kidneys were usually hyperæmic, and contained little hæmorrhages. There was also general encephalic engorgement, and in one experiment intense congestion of the meninges was observed. Few opportunities have presented themselves for pathological observations relative to the effects produced by ferric chloride on man. In a case related by Christison, in which a man swallowed 42·4 c.c. (1¹⁄₂ oz.) of the tincture, and died in five weeks, there was found thickening and inflammation of the pyloric end of the stomach.

The case of Char——, already alluded to, is that in which the most complete details of the autopsy are recorded, and they coincide very fairly with those observed in animals; the tongue was covered with a greenish fur, bordered at the edges with a black substance, described as being like “mud”; the lining membrane of the gullet was pale, but also covered with this dark “mud.” The stomach contained a greenish-black liquid; the liver was large and congested; the kidneys were swollen, congested, and ecchymosed; the cerebral membranes were gorged with blood, and the whole brain hyperæmic.

§ 881. Ferrous Sulphate, Copperas, or Green Vitriol, FeSO₄7H₂O = 152 + 126; specific gravity, anhydrous, 3·138; crystals, 1·857; composition in 100 parts, FeO, 25·92; SO₃, 28·77; H₂O, 45·32.—This salt is in beautiful, transparent, bluish-green, rhomboidal prisms. The crystals have an astringent, styptic taste, are insoluble in alcohol, but dissolve in about 1·5 times their weight of water; the commercial article nearly always responds to the tests, both for ferrous and ferric salts, containing a little persalt. The medicinal dose of this salt is usually given as from ·0648 to ·324 grm. (1 to 5 grains), but it has been prescribed in cases requiring it in gramme (15·4 grains) doses without injury. Sulphate of iron has many technical applications; is employed by all shoemakers, and is in common use as a disinfectant. The salt has been employed for criminal purposes in France, and in this country it is a popular abortive. In recorded cases, the symptoms, as well as the pathological appearances, have a striking resemblance to those produced by the chloride. There are usually colic, vomiting, and purging; but in one case (reported by Chevallier), in which a man gave a large dose of sulphate of iron to his wife, there was neither vomiting nor colic; the woman lost her appetite, but slowly recovered. Probably the action of ferrous sulphate, like that of the chloride, is profoundly modified by the presence or absence of food in the stomach. Anything like 28·3 grms. (an ounce) of sulphate of iron must be considered a dangerous dose, for, though recovery has taken place from this quantity, the symptoms have been of a violent kind.

§ 882. Search for Iron Salts in the Contents of the Stomach, &c.—Iron, being a natural component of the body, care must be taken not to confound the iron of the blood or tissues with the “iron” of a soluble salt. Orfila attempted to distinguish between the two kinds of iron by treating the contents of the stomach, the intestines, and even the tissues, with cold acetic acid, and allowing them to digest in it for many hours before filtering and testing for iron in the filtrate, and this is generally the process which has been adopted. The acid filtrate is first treated with sulphuretted hydrogen, which gives no precipitate with iron, and then with sulphide of ammonium, which precipitates iron black. The iron sulphide may be dissolved by a little hydrochloric acid and a drop of nitric acid, and farther identified by its forming Prussian blue when tested by ferrocyanide of potash, or by the bulky precipitate of oxide, when the acid liquid is alkalised by ammonia. In the case of Duf——, the experts attempted to prove the existence of foreign iron in the liver by taking 100 grms. of Duf——’s liver and 100 grms. of the liver of a non-poisoned person, and destroying each by nitro-muriatic acid, and estimating in each acid solution the ferric oxide. Duf——’s liver yielded in 100 parts ·08 mgrm. of ferric oxide, the normal liver ·022—nearly three times less than Duf——’s.

To obtain iron from the urine, the fluid must be evaporated down to a syrup in a platinum dish, a little nitric acid added, heated, and finally completely carbonised. The residue is dissolved in hydrochloric acid. Normal urine always contains an unweighable trace of iron; and, therefore, any quantity, such as a mgrm. of ferric oxide, obtained by careful precipitation of the hydrochloric acid solution out of 200 to 300 c.c. of urine, would be good evidence that a soluble salt of iron had been taken. The hydrochloric acid solution is first precipitated by ammonia and ammonic sulphide. The precipitate thus obtained will not be pure iron sulphide, but mixed with the earth phosphates. It should be redissolved in HCl, precipitated by sodic carbonate, then acidified by acetic acid and sodic acetate added, and the solution well boiled; the iron will then be precipitated for the most part as oxide mixed with a little phosphate of iron.

Since, as before mentioned, a great portion of the iron swallowed as a soluble salt is converted into insoluble compounds and excreted by the fæces, it is, in any case where poisoning by iron is suspected, of more importance to examine chemically the fæces and the whole length of the alimentary canal, than even the contents of the stomach. In particular, any black material lying on the mucous membrane may be sulphide of iron mixed with mucus, &c., and should be detached, dissolved in a little hydrochloric acid, and the usual tests applied.

In the criminal cases alluded to, there were iron stains on certain linen garments which acquired an importance, for, on dissolving by the aid of nitric acid, they gave the reactions of chlorine and iron. Any stains found should be cut out, steeped in water, and boiled. If no iron is dissolved the stain should then be treated with dilute nitric acid, and the liquid tested with ferrocyanide of potash, &c. It need scarcely be observed that iron-mould is so common on shirts and any fabric capable of being washed, that great care must be exercised in drawing conclusions from insoluble deposits of the oxide.

2. CHROMIUM.

§ 883. The only salts of chromium of toxicological importance are the neutral chromate of potash, the bichromate of potash, and the chromate of lead.

Neutral Chromate of Potash, CrO₃K₂O = 194·7, containing 56·7 per cent. of its weight of chromic anhydride, CrO₃.—This salt is in the form of citron-yellow rhombic crystals, easily soluble in water, but insoluble in alcohol. Its aqueous solution is precipitated yellow by lead acetate or basic acetate; the precipitate being insoluble in acetic acid. If chromate of potash in solution is tested with silver nitrate, the red chromate of silver is thrown down; the precipitate is with difficulty soluble in dilute nitric acid.

§ 884. Potassic Bichromate, CrO₃K₂O = 295·2, containing 68·07 per cent. of its weight of chromic anhydride, CrO₃.—This salt is in beautiful large, red, transparent, four-sided tables; it is anhydrous and fuses below redness. At a high temperature it is decomposed into green oxide of chromium and yellow chromate of potash. It is insoluble in alcohol, but readily soluble in water. The solution gives the same precipitates with silver, lead, and barium as the neutral chromate. On digesting a solution of the bichromate with sulphuric acid and alcohol, the solution becomes green from the formation of chromic oxide.

§ 885. Neutral Lead Chromate, PbCrO₄ = 323·5, composition in 100 parts, PbO, 68·94, CrO₃, 31·06.—This is technically known as “Chrome Yellow,” and is obtained as a yellow precipitate whenever a solution of plumbic acetate is added, either to the solutions of potassic chromate or bichromate; by adding chrome yellow to fused potassic nitrate, “chrome red” is formed; it has the composition CrO₃2PbO. Neutral lead chromate is insoluble in acids, but may be dissolved by potassic or sodic hydrates.

§ 886. Use in the Arts.—Potassic bichromate is extensively used in the arts—in dyeing, calico-printing, the manufacture of porcelain, and in photography; the neutral chromate has been employed to a small extent as a medicine, and is a common laboratory reagent; lead chromate is a valuable pigment.

§ 887. Effects of some of the Chromium Compounds on Animal Life.—In the chromates of potash there is a combination of two poisonous metals, so that it is not surprising that Gmelin found the chloride of chromium, CrCl₃, less active than the neutral chromate of potash; 1·9 grm. of the last, administered to a rabbit by the stomach, caused death within two hours, while 3 grms. of chromous chloride had no action. Subcutaneous doses of ·2 to ·4 grm. of neutral chromate (according to the experiments of E. Gergens[960] and Carl Posner[961]) act with great intensity on rabbits. Immediately after the injection the animals are restless, and show marked dyspnœa; death often takes place within a few hours.