V.—ALKALINE EARTHS.
Barium.
§ 902. The soluble salts of barium are undoubtedly poisonous, and are of frequent occurrence in the arts. The chloride of barium is used in the staining of wool, the nitrate and the chlorate in the green fires of the pyrotechnist, the oxide and the carbonate in the manufacture of glass. The chromate is used by artists under the name of “yellow ultramarine,” while the sulphate, technically known as “permanent white,” is, on account of its weight and cheapness, occasionally used as an adulterant of white powders and other substances. Barium sulphide, under various names, such as Bottcher’s depilatory, Thompson’s hair destroyer, Poudre épilatoire, and other names, is in commerce, and has caused poisonous symptoms.[978]
[978] Barium carbonate and sulphate are usually enumerated as occasional adulterants of bread, but there is no modern authentic instance of this.
§ 903. Chloride of Barium, BaCl22H2O 208 + 36; anhydrous, Ba, 65·86 per cent., Cl, 34·14; specific gravity, 3·75, is in commerce in the form of white, four-sided, tabular crystals; water dissolves about half its weight at ordinary temperatures, three-fourths at 100°. Its solution gives a white precipitate with sulphuric acid, quite insoluble in water and nitric acid.
The salt imparts a green hue to an otherwise colourless flame; viewed by the spectroscope, green bands will be visible. We may note that chloride of barium gives two different spectra—the one at the moment of the introduction of the salt, the other when the substance has been exposed for some time to a high temperature. This is caused by a rapid loss of chlorine, so that the first spectrum is due to BaCl2, with a variable mixture of BaCl, the second to BaCl alone.
§ 904. Baric Carbonate, BaCO3 = 197; specific gravity, 4·3; BaO, 77·69 per cent., CO2, 22·31, in its native form termed Witherite, is a dense, heavy powder, insoluble in pure water, but dissolving in acetic, nitric, and hydrochloric acids, the solution giving the reactions of barium.
A rat-poison may be met with composed of baric carbonate, sugar, and oatmeal, flavoured with a little oil of aniseed and caraway.
§ 905. Sulphate of Barium, BaSO4; specific gravity, 4·59; BaO, 65·66 per cent., SO3, 34·34 per cent., is a pure white powder when recently precipitated, absolutely insoluble in water, and practically insoluble in cold dilute acids. It is quite unalterable in the air at a red heat; on ignition with charcoal, it may be converted almost entirely into sulphide of barium; and by ignition with CaCl2 into chloride.
§ 906. Effects of the Soluble Salts of Barium on Animals.—One of the early notices of the poisonous characters of barium compounds was by James Watt,[979] who found that witherite, given to dogs, produced vomiting, diarrhœa, and death in a few hours. Sir Benj. Brodie[980] administered barium chloride, and noticed its paralysing effect on the heart. Orfila[981] made several experiments, and observed that 4 grms. of the carbonate produced death in dogs in periods varying from one to five hours; but in these experiments the gullet was tied. The later investigators have been Gmelin, Onsum, Cyon, and Böhm.[982] Gmelin found barium carbonate and barium chloride act in a very similar manner; and, indeed, it is improbable that barium carbonate, as carbonate, has any action, but, when swallowed, the hydrochloric and other acids of the stomach form with it soluble compounds. J. Onsum made eight experiments with both barium carbonate and chloride on animals. The respiration was quickened and, at the same time, made weak and shallow; the heart’s action was accelerated; the animals became restless: and there was great muscular prostration, with paralytic symptoms; convulsions did not occur in any one of the eight animals. He found, on post-mortem examination, the right side of the heart full of blood from backward engorgement; he describes a plugging of the small arteries with little fibrinous coagula, having an inorganic nucleus, with constant hæmorrhagic extravasations. Onsum seems to have held the theory that the baryta salts circulated in the blood, and then formed insoluble compounds, which were arrested in the lungs, causing minute emboli, just in the same way as if a finely-divided solid were introduced directly into the circulation by the jugular vein.
[979] Memoirs of the Literary and Philosophical Society of Manchester, 1790, vol. iii. p. 609.
[980] Phil. Trans., 1812.
[981] Traité des Poisons, 3rd ed., t. i., Paris, 1826.
[982] Gmelin, C. G., Versuche über die Wirkungen des Baryts, Strontians, Chroms, Molybdäns, Wolframs, Tellurs, u. s. w. auf den thierischen Organismus, Tübingen, 1824; Onsum, J., Virchow’s Archiv, Bd. 2, 1863; Cyon, M., Archiv f. Anatomie, Physiologie, &c., 1866; Böhm, Archiv f. experiment. Pathol., Bd. 3, 1874.
Onsum stands alone in this view. Cyon found no emboli in the lungs, and refers the toxic effect to a paralysing influence on the heart and voluntary muscles, and also on the spinal cord. Cyon, to settle the embolic theory, injected into the one jugular vein of a rabbit barium chloride, and into the other sodic sulphate, but the small arteries and capillaries of the lungs remained clear. Böhm, operating on frogs, found a great similarity between the action of small doses of barium salts and that of certain organic poisons; as, for example, cicutoxin, ·012 to ·02 grm. subcutaneously injected into frogs, acted as a heart-poison. So also Blake[983] found the heart slowed, and concluded that barium chloride had a direct action on the cardiac muscle, and also a toxic influence on the nervous system. F. A. Falck, in experiments on rabbits, found a great reduction of temperature after poisoning with barium chloride (3° to 12·6°).
[983] Journ. of Anat. and Physiol. 2nd series, 1874.
§ 907. Effects of the Salts of Barium on Man.—There were about fifteen cases of poisoning by barium salts on record by the end of 1883—three of which were suicidal, but most of them were due to accident or mistake. In three cases, barium chloride was taken instead of Glauber’s salts; in one, instead of Carlsbad salts; in another, a mixture of barium nitrate and sulphur, instead of pure sulphur; in a sixth case, a mixture of barium acetate and raspberry syrup, instead of sodic ethylsulphate; in a seventh, a chemist put a larger dose than was ordered by the prescription; and in four cases barium carbonate had been mixed with flour, and this flour used in the making of pastry. Of the fifteen cases, nine, or 60 per cent., proved fatal; the fifteen cases have now (1894) been increased to twenty-six.
Fatal Dose.—The recorded cases of poisoning have not satisfactorily settled the question as to the least fatal dose of the barium salts. 6·5 grms. (about 100 grains) of the chloride have destroyed the life of an adult woman in fifteen hours; 14 grms. (1⁄2 oz.) of the nitrate of baryta have killed a man in six and a half hours; and the carbonate of baryta has destroyed a person in the relatively small dose of 3·8 grms. (60 grains). On the other hand, certain Continental physicians have prescribed barium chloride in large medicinal doses; for example, Pirondi[984] and Lisfranc[985] have gradually raised the dose of barium chloride from 4 decigrams up to 3 grms. (48 grains) daily, given, of course, in divided doses. Pirondi himself took in a day 7·7 grms. (119 grains) without bad effect.
[984] De la Tumeur Blanche de Genou, éd. 2, Paris, 1836.
[985] Gaz. Med. de Paris, 1835, No. 14.
§ 908. Symptoms.—The local action of barium salts must be sharply distinguished from the action of the absorbed salts. Kobert divides the symptoms into seven groups:—
(1) Local, consisting in malaise, nausea, salivation, vomiting, and pain in the stomach. This group merges so much into the next as hardly to admit of precise separation.
(2) Excitation of the alimentary canal, both of the nervous and muscular apparatus. Hence vomiting, painful colic, and acute diarrhœa. All these phenomena may be produced in animals by subcutaneous injection, and, therefore, do not depend alone upon local action.
(3) Excitation of the brain motor centres, which leads to convulsions, or may result in paralysis. About half the recorded cases of barium poisoning in the human subject have been convulsed; the other half paralysed. In one case mania resulted.
(4) Weakness or destruction of the power of muscular contraction; this produces in frogs, when the muscular test movements are recorded graphically, a veratrin-like convulsion curve. In the human subject the effect is that of great muscular weakness.
(5) Digitalin-like influence on the heart and blood-vessels, showing itself in great slowing of the pulse, præcordial anxiety, and strong beating of the heart (not only sensible to the patient, but which can be heard and felt by the bystanders). The arteries are incompressible and rigid, the blood-pressure strikingly raised. The blood-vessels of old people do not stand the pressure, hence hæmorrhages in the lungs, stomach, and other organs. Frogs die with the heart in systole.
(6) Catarrhal affection of the conjunctiva, the mucous membrane of the respiratory tract, and the nose.
(7) Formation of insoluble baryta salts in the blood-vessels, according to Onsum. This has not been observed in man, and the fact is disputed (see ante).
In Dr. Tidy’s case,[986] in which a man, suffering from rheumatism, but otherwise healthy, took a mixture of barium nitrate, flowers of sulphur, and potassic chlorate, instead of sulphur, the symptoms were blisters on the tongue, a burning pain in the gullet and stomach, with vomiting, diarrhœa, convulsions, aphonia, and coldness of the extremities. A case, copiously detailed by Seidel,[987] in which a pregnant woman, twenty-eight years old, took carbonate of baryta for the purpose of self-destruction, is interesting. She probably took the poison some little time before six in the evening; she vomited and had great pain in the stomach, but slept during the night without further sickness. The next morning, after drinking some coffee, the sickness was renewed; nevertheless, at 7 A.M., she repaired to her employment, which was distant an hour’s walk; she probably suffered much on the way, for she did not arrive until 9 A.M. The vomiting, accompanied by diarrhœa, continuing, she was sent to bed at 2 P.M. She was very cold, and complained of great weakness; the vomiting now ceased. At 8 P.M. she shivered violently, could scarcely swallow, and the respiration was oppressed. At 11 she seemed a little improved; but at 3 A.M. she was found much worse, breathing rapidly, but fully conscious; at 4 A.M. she was again seen, but found dead; she thus lived about thirty-four hours after taking the fatal dose.
[986] Pharm. Journ., June 1868.
[987] Eulenberg’s Vierteljahrsschrift f. ger. Med., Bd. 27, § 213.
§ 909. Distribution of Barium in the Body.—Neumann has shown that, after repeated injection of insoluble barium sulphate into the veins of rabbits, barium is to be found in the liver, kidneys, spleen, and spinal cord, but not in the muscles, thymus, or brain. G. Linossier[988] has made a similar series of experiments, but with the more soluble carbonate, and this salt was injected into animals for a period of thirty days. All the organs contained some barium; lungs, muscles, and the heart only contained traces, the liver rather more, the kidneys, brain, and spinal cord still more, and, lastly, the bones a considerable quantity, as much as 0·056 per cent.
[988] Compt. rend. Soc. Biol. (8), iv. 122-123.
§ 910. Post-mortem Appearances.—The post-mortem appearances are usually changes in the stomach and intestinal tract, but there are only rarely traces of great inflammation. It is true, that in a case recorded by Wach,[989] perforation of the stomach was found; but, since there was old-standing disease of both liver and stomach, it is not clear that this is to be attributed entirely to poison. In the case of suicide just detailed, the mucous membrane of the stomach was much ecchymosed; over the whole were strewn little white grains, sticking to the mucous membrane, and there were also ecchymoses in the duodenum.
[989] Henke’s Zeitschrift f. Staatsarzneik., 1835, Bd. 30, Hft. 1, § 1.
§ 911. The Separation of Barium Salts from Organic Solids or Fluids, and their Identification.—In the usual course of examination of an unknown substance, the matter will already have been extracted by hydrochloric acid, and the solution successively treated with hydric and ammonic sulphides. The filtrate from any precipitate, after being boiled, would in such a case give a precipitate if treated with sulphuric acid, should a salt of barium soluble in hydrochloric acid be present.
If there, however, should be special grounds to search for baryta in particular, it is best to extract the substances with pure boiling water, to concentrate the solution, and then add sulphuric acid, collecting any precipitate which may form. If the latter is found to be sulphate of baryta, it must be derived from some soluble salt, such as the nitrate or the chloride. The substances which have been exhausted with water are now treated with hydrochloric acid, and to the acid filtrate sulphuric acid is added. If sulphate of baryta is thrown down, the baryta present must have been a salt, insoluble in water, soluble in acids—probably the carbonate. Lastly, the organic substances may be burnt to an ash, the ash fused with carbonate of soda, the mass, when cool, dissolved in HCl, and the solution precipitated with sulphuric acid. Any baryta now obtained was present, probably in the form of sulphate; nevertheless, if obtained from the tissues, it would prove that a soluble salt had been administered, for (so far as is known) sulphate of barium is not taken up by the animal fluids, and is innocuous.
The sulphate of barium is identified as follows:—
(1) A part of the well-washed precipitate is boiled with distilled water, filtered, and to the filtrate a solution of chloride of barium added. If there is no precipitate, the sulphate can be none other than baric sulphate, for all the rest, without exception, are soluble enough to give a slight cloud with baric chloride.
(2) The sulphate may be changed into sulphide by ignition on charcoal, the sulphide treated with HCl, the solution evaporated to dryness, and the resulting chloride examined spectroscopically; or, the sulphide may be mixed with chloride of calcium, taken up on a loop of platinum wire, heated strongly in the flame of a Bunsen burner, and the flame examined by the spectroscope.
(3) A solution of the chloride of barium obtained from (2) gives a yellow precipitate with neutral chromate of potash, insoluble in water, but soluble in nitric acid.