Treatise on Poisons by Sir Robert Christison

OF POISONING WITH BARYTA. Baryta and its salts, the last genus of the metallic irritants which requires particular notice, are commonly arranged among earthy substances, but on account of their chemical and physiological properties, may be correctly considered in the present place. These poisons are worthy of notice, because they are not only energetic, but likewise easily procured, so that they may be more extensively used, when more generally known. SECTION I.—_Of the Chemical Tests for the preparations of Baryta._ Three compounds of this substance may be mentioned, the pure earth or oxide, the muriate, or chloride of barium, and the carbonate. The pure earth, however, is so little seen, that it is unnecessary to describe its chemical or physiological properties. The _Carbonate of Baryta_ is met with in two states. Sometimes it is native, and then commonly occurs in radiated crystalline masses, of different degrees of coarseness of fibre, nearly colourless, very heavy, and effervescing with diluted muriatic acid. It is also sold in the shops in the form of a fine powder of a white colour, prepared artificially by precipitating a soluble salt of baryta with an alkaline carbonate. It is best known by its colour, insolubility in water, solubility with effervescence in muriatic acid, and the properties of the resulting muriate of baryta. The _Muriate of Baryta_, or chloride of barium, is the most common of the compounds of this earth, having been for some time used in medicine for scrofulous and other constitutional disorders. It is procured either by evaporating the solution of the carbonate in hydrochloric acid, or by decomposing a more common mineral, the sulphate, by means of charcoal aided by heat, dissolving in boiling water the sulphuret so formed, and decomposing this sulphuret by hydrochloric acid. It is commonly met with in the shops irregularly crystallized in tables. It has an acrid, irritating taste, is permanent in the air, and dissolves in two parts and a half of temperate water. The solution is distinguished from other substances by the following chemical characters. From all other metallic poisons hitherto mentioned, it is easily distinguished by means of hydrosulphuric acid, which does not cause any change in barytic solutions. From the alkaline and magnesian salts it is distinguished by the effects of the alkaline sulphates, which have no visible action except on the barytic solution, and cause in it a heavy white precipitate, insoluble in nitric acid. From the chlorides of calcium and strontium, it is to be distinguished by evaporating the solution till it crystallizes. The crystals are known not to be chloride of calcium, because they are not deliquescent. The chloride of strontium (which resembles that of barium in many properties, but which must be carefully distinguished, as it is not poisonous), differs in the form of the crystals, which are delicate six-sided prisms, while those of the barytic salt are four-sided tables, often truncated on two opposite angles, sometimes on all four,—by its solubility in alcohol, which does not take up the chloride of barium,—and by its effect on the flame of alcohol, which it colours rose-red, while the barytic salts colour it yellow. The chloride of barium is known from other soluble barytic salts, by the action of nitrate of silver, which throws down a white precipitate. Vegetable and animal fluids do not decompose the solution of chloride of barium, except by reason of the sulphates and carbonates which most of them contain in small quantities. But the action of its tests may be distinguished, although the salt has not undergone decomposition. In that case the most convenient method of analysis is to add a little nitric acid, which will dissolve any carbonate of baryta that may have been formed,—to filter and then throw down the whole baryta in the form of sulphate, by means of the sulphate of soda,—and to collect the precipitate, and calcine it with charcoal for half an hour in a platinum spoon or earthen crucible, according to the quantity. A sulphuret of baryta will thus be procured, which is to be dissolved out by boiling water, and decomposed after filtration by muriatic acid. A pure solution is thus easily obtained. Orfila has lately proposed a process more complex in its details, but the same in principle.[1380] SECTION II.—_Of the Action of the Salts of Baryta, and the Symptoms they excite in Man._ The action of the barytic salts on the body is energetic. Like most metallic poisons, they seem to possess a twofold action,—one local and irritating, the other remote and indicated by narcotic symptoms. This narcotic action is more decided and invariable than in the instance of any of the metallic poisons hitherto noticed. Such at least is the result of the experiments of Sir B. Brodie,[1381] which have since been amply confirmed by Professor Orfila[1382] and Professor Gmelin.[1383] Orfila found that when the chloride was injected into the veins of a dog in the dose of five grains only, death ensued in six minutes, and was preceded by convulsions, at first partial, but afterwards affecting the whole body. Sir B. Brodie found the same effects follow in twenty minutes, when ten grains were applied to a wound in the back of a rabbit,—the convulsions being preceded by palsy, and ending in coma. Half an ounce when injected into the stomach excited the same symptoms in a cat, and proved fatal in sixty-five minutes, though the animal vomited. Schloepfer observed, that when a scruple, dissolved in two drachms of water, was injected into the windpipe of a rabbit, it fell down immediately, threw back its head, was convulsed in the fore-legs, and died in twelve minutes.[1384] Gmelin observed in his experiments that it caused slight inflammation of the stomach, and strong symptoms of an action on the brain, spine, and voluntary muscles. He found the voluntary muscles destitute of contractility immediately after death; yet the heart continued to contract vigorously for some time, even without the application of any stimulus. From some experiments made on horses by Huzard and Biron, by order of the Société de Santé of Paris, it appears that the hydrochlorate, when given to these animals in the dose of two drachms daily, produced sudden death about the fifteenth day, without previous symptoms of any consequence.[1385] In the experiments now related, very little appearance of inflammation was found in the parts to which the poison was directly applied. It is also worthy of remark that the heart does not seem to have been particularly affected; and yet according to the recent researches of Mr. Blake, the barytic salts are the most powerful of all inorganic poisons in their action on the heart, when they are injected into the veins. A quarter of a grain of the chloride appreciably depresses arterial action; two grains completely arrest the heart’s contractions in twelve seconds; and when it is injected back into the aorta from the axillary artery, it causes at first some obstruction to the capillary circulation, but soon arrests the action of the heart, as when it is introduced into the veins.[1386] The pure earth appears to produce nearly the same effects in an inferior dose. When swallowed, the symptoms of local irritation are more violent; but death ensues in a very short space of time, and is preceded by convulsions and insensibility. The stomach after death is found of a reddish-black colour, and frequently with spots of extravasated blood in its villous coat. The carbonate in a state of minute division is scarcely less active than the hydrochlorate, since it is dissolved by the acid juices of the stomach. A drachm killed a dog in six hours; vomiting, expressions of pain, and an approach to insensibility preceded death; and marks of inflammation were found in the stomach.[1387] Pelletier made many experiments on the poisonous properties of the carbonate. Fifteen grains of the native carbonate killed one dog in eight hours, and another in fifteen.[1388] Dr. Campbell found it to be a dangerous poison, even when applied externally. Twelve grains introduced into a wound in the neck of a cat, excited on the third day languor, slow respiration, and feeble pulse; towards evening the animal became affected with convulsions of the hind-legs and with dilated pupils; and death followed not long afterwards.[1389] This substance, before its real nature was known, used at one time to be employed in some parts of England as a variety of arsenic for poisoning rats. The salts of baryta are absorbed in the course of their action. The chloride has been detected by Dr. Kramer both in the blood and urine by incineration with carbonate of potash, washing the ashes with weak solution of carbonate of potash, dissolving the residue in diluted nitric acid, and testing the solution for baryta.[1390] Orfila has also obtained baryta, by his process alluded to above, in the liver, kidneys, and spleen of animals killed by the chloride.[1391] The symptoms produced by the salts of baryta in man have seldom been particularly described. An instance is shortly noticed in the Journal of Science, where an ounce of the hydrochlorate was taken by mistake for Glauber’s salt, and proved fatal. The patient immediately after swallowing it felt a sense of burning in the stomach; vomiting, convulsions, headache, and deafness ensued; and death took place within an hour.[1392] A similar case, fatal in two hours, has been related by Dr. Wach of Merseburg. A middle-aged woman who, though generally in good health, had suffered for a day or two from pains in the stomach, took one morning a solution of half an ounce of chloride of barium by mistake for sulphate of soda. She was soon seized with sickness, retching, convulsive twitches of the hands and feet, vomiting of clear mucus, great anxiety, restlessness, and loss of voice; and she died under constant efforts to vomit, and violent convulsive movements, but with her faculties entire.[1393] Unpleasant effects have been observed from too large doses of the chloride administered medicinally. A case is mentioned in the Medical Commentaries of a gentleman who was directed to take a solution as a stomachic, but swallowed one evening by accident so much as seventy or eighty drops. He had soon after profuse purging without tormina, then vomiting, and half an hour after swallowing the salt excessive muscular debility, amounting to absolute paraplegia of the limbs. This state lasted about twenty-four hours, and then gradually went off.[1394] I have known violent vomiting, gripes, and diarrhœa produced in like manner by a quantity not much exceeding the usual medicinal doses. Dr. Wilson of London has lately described a distinct case of poisoning with the carbonate. The quantity taken was half a tea-cupful; but emetics were given, and operated before any symptoms showed themselves. In two hours the patient complained of dimness of sight, double vision, headache, tinnitus, and a sense of distension in the stomach, and subsequently of pains in the knees and cramps of the legs, with occasional vomiting and purging next day; for some days afterwards the head symptoms continued, though more mildly, and she was much subject to severe palpitations; but she was in the way of recovery when the account of her case was published.[1395] Mr. Parkes mentions that, according to information communicated to him by the proprietor of an estate in Lancashire, where carbonate of baryta abounds, many domestic animals on his estate died in consequence of licking the dust of the carbonate, and that it once proved fatal to two persons, a woman and her child, who took each about a drachm.[1396] Dr. Johnstone says he once swallowed ten grains of this compound, without experiencing any bad effect.[1397] SECTION III.—_Of the Morbid Appearances caused by the Salts of Baryta._ In animals the mucous membrane of the stomach is usually found of a deep-red colour, unless death take place with great rapidity, in which case the alimentary canal is healthy. In all the animals, which in Dr. Campbell’s experiments were killed by the application of the muriate to wounds, the brain and its membranes were much injected with blood; and in one of them the appearances were precisely those of congestive apoplexy. In Wach’s case the stomach was dark brownish-red externally, and the small intestines brighter red. Internally the stomach presented uniform deep redness, with clots of blood, and bloody mucus scattered over it; and near the cardiac end there was a perforation, above half an inch in diameter within, and half as wide at the outside, and surrounded with swollen edges and extensive thickening of the villous coat. The small intestines were internally very red and lined with red mucus interspersed with clots of blood. The great intestines were extremely contracted. The lungs were gorged, the heart full of dark liquid blood, and the cerebral vessels distended. Chloride of barium was detected in the stomach and intestines. The perforation in this case was evidently an accidental concurrence. SECTION IV.—_Of the Treatment._ The treatment of this variety of poisoning consists chiefly in the speedy administration of some alkaline or earthy sulphate, such as the sulphate of soda or sulphate of magnesia. The poison is thus immediately converted into the insoluble sulphate of baryta, which is quite inert. Two drachms of muriate of baryta were injected by Orfila into the stomach of a dog, and eight minutes afterwards two drachms of sulphate of soda. The gullet was then secured by a ligature. At first efforts were made to vomit, and in an hour sulphate of baryta was discharged with the alvine evacuations. There was neither insensibility nor convulsions; and the next morning the animal evidently suffered only from the ligature on the gullet. This fact not only proves the efficacy of the sulphate, but likewise shows that in the kinds of poisoning where diarrhœa occurs, the poison is very soon discharged, and ought therefore to be looked for in the evacuations from the bowels.[1398] A few observations may be here added on the effects of the salts of _strontia_ on the animal frame. These compounds bear a close resemblance to the salts of baryta, and the two earths were consequently long confounded together till Dr. Hope pointed out their distinctions. One of the most striking differences is, that the salts of the strontia are very feebly poisonous. Some experiments of this purport were made by M. Pelletier of Paris,[1399] and by Blumenbach; but the most accurate researches are those of Professor Gmelin. He found that ten grains of the chloride in solution had no effect when injected into the jugular vein of a dog,—that two drachms had no effect when introduced into the stomach of a rabbit,—that half an ounce was required to cause death in that way,—that two drachms of the carbonate had no effect,—and that two drachms of the nitrate, dissolved in six parts of water and given to a rabbit, merely caused increase of the frequency and hardness of the pulse and a brisk diarrhœa.[1400] Mr. Blake also found that small doses of the salts of strontia have little effect when injected into the veins; but that forty grains arrest the action of the heart in fifteen seconds.[1401]