Chapter LI: Part IX: Inorganic Poisons (9)

In the case quoted of the woman who poisoned herself with potassic chromate, very striking changes were found in the stomach and intestines. The stomach contained above a litre of dark chocolate fluid of alkaline reaction; the mucous membrane, in the neighbourhood of the cardiac and pyloric extremities, was swollen and red in sharply defined patches; portions of the epithelial layer were detached, the rest of the mucous membrane was of a yellow-brown colour, and the whole intestine, from the duodenum to the sigmoid flexure, was filled with a partly bloody, partly treacly-looking fluid; the mucous membrane, throughout its entire extent, was swollen, with numerous extravasations, and in places there were losses of substance. Similar appearances to these have been found in other instances; the anomalous case recorded by Mr. Wilson (_ante_) is an exception. In this instance a pint of inky, turbid liquid, which yielded to analysis potassic bichromate, was found in the stomach; but there were no marked changes anywhere, save a slight redness of the cardiac end of the gullet. In Linstow’s two cases of poisoning by lead chromate, there were found in both fatty degeneration of the liver cells, and red points or patches of redness in the stomach and intestines. In the elder boy the changes in the duodenum were very intense, the mucous membrane was swollen and easily detached, in the upper part strongly injected with blood; in one place there was a perforation, and in several places the membrane was extremely thin. In the younger boy the kidneys seem to have been normal, in the elder congested and containing pus. Although it was clear that the two children died from lead chromate, a chemical analysis gave no result.

§ 892. =Detection of the Chromates and Separation of the Salts of Chromium from the Contents of the Stomach, &c.=--If in the methodical examination of an acid liquid, which has been already filtered from any precipitate that may have been obtained by sulphuretted hydrogen, this liquid is made alkaline (the alkali only being added in slight excess), and hydrated chromic oxide is thrown down mixed, it may be with other metals of the second class, the precipitate may then be fused with nitre and potassic carbonate, and will yield potassic chromate, soluble in water, and recognised by the red precipitate which it gives with silver nitrate, the yellow with lead acetate, and the green colour produced by boiling with dilute sulphuric acid and a little alcohol or sugar. If by treating a complex liquid with ammonium hydrosulphide, sulphides of zinc, manganese, and iron are thrown down mixed with chromic oxide, the same principles apply. If a chromate is present in the contents of the stomach, and the organic fluid is treated with hydrochloric acid and potassic chlorate, chromic chloride is formed, and dissolving imparts a green colour to the liquid--this in itself will be strong evidence of the presence of a chromate, but it should be supplemented by throwing down the oxide, and transforming it in the way detailed into potassic chromate.

A general method of detecting and estimating both chromium and barium in organic matters has been worked out by L. de Koningh.[972] The substances are burnt to an ash in a platinum dish. The ash is weighed; to the ash is added four times its weight of potassium sodium carbonate and the same amount of potassium nitrate; and the whole is fused for fifteen minutes. The fused mass is boiled with water and filtered; if chromium is present, the filtrate is of a more or less pronounced yellow colour, but manganese may produce a green colour and mask the yellow; this colour is removed by boiling with a little alcohol. The liquid is concentrated down to 20 c.c., filtered into a test-tube, and a colorimetric estimation made of the chromium present by imitating the colour by a solution of potassium chromate of known strength. To prove that the colour is really due to chromium, acetic acid and lead acetate are added, when the yellow chromate of lead is at once thrown down. (If lead was in the ash, a yellow precipitate may appear on the addition of acetic acid.) To the portion of ash insoluble in water strong hydrochloric acid is added, and to the acid solution a large excess of calcium sulphate is added; this precipitates barium as sulphate free from lead sulphate, for, if the latter should be present, it does not, under the circumstances, come down, being soluble in strong hydrochloric acid.

[972] _Arch. Pharm._ (3), xxvii. 944.

3. THALLIUM.

§ 893. Thallium was discovered by Crookes in 1861. Its atomic weight
is 204; specific gravity, 11·81 to 11·91; melting-point, 290°. It is
a heavy diamagnetic metal, very similar to lead in its physical
properties. The nitrate and sulphate of thallium are both soluble in
water, the carbonate less so, requiring about 25 parts of water for
solution, while the chloride is sparingly soluble, especially in
hydrochloric acid.

§ 894. =Effects.=--All the salts of thallium are poisonous. One of
the earlier experimenters on the physiological action, Paulet, found
1 grm. (15·4 grains) of thallium carbonate sufficient to kill a
rabbit in a few hours; there were loss of muscular power, trembling
of the limbs, and death apparently from asphyxia. Lamy[973] used
thallium sulphate, and found that dogs were salivated, and suffered
from trembling of the limbs, followed by paralysis. The most
definite results were obtained by Marmé,[974] who found that ·04 to
·06 grm. of a soluble thallium salt, injected subcutaneously or
directly into the veins, and ·5 grm. administered through the
stomach of rabbits, caused death. The action is cumulative, and
something like that of mercury: there are redness and swelling of
the mucous membrane of the stomach, with mucous bloody discharges;
hæmorrhage may also occur from the lungs. Thallium is eliminated
through the urine, and is also found in the fæces; it passes into
the urine from three to five minutes after injection: the
elimination is slow, often taking as long as three weeks. It has
been found in the milk, in the tears, in the mucous membrane of the
mouth, of the trachea, in the secretion of the gastric mucous
membrane, and in the pericardial fluid; and in these places, whether
the poison has been introduced by subcutaneous injection, or by any
other channel. It seems probable that the reason of its being
detected so readily in all the secretions is the minute quantity
which can be discovered by spectroscopic analysis.

[973] _Chem. News_, 1863.

[974] _Göttinger Gelehrt. Nachrichten_, Aug. 14, No. 20.

§ 895. =Separation of Thallium from Organic Fluids or Tissues.=--The
salts of thallium, if absorbed, would only be extracted in traces
from the tissues by hydrochloric acid, so that, in any special
search, the tissues are best destroyed by either sulphuric or nitric
acid, or both. In the ordinary method of analysis, when an acid
liquid is first treated with sulphuretted hydrogen, and then made
alkaline by ammonia and ammonic sulphide, thallium would be thrown
down with the manganese and iron of the blood. From the mixed
sulphides, thallium may be separated by oxidising and dissolving the
sulphides with nitric acid, evaporating off the excess of acid,
dissolving in a very little hot water, and precipitating thallous
chloride by solution of common salt. The ease, however, with which
thallium may be separated from solutions of its salts by galvanism
is so great as to render all other processes unnecessary: the best
way, therefore, is to obtain a deposit of the metal on platinum by a
current from one or more cells, and then to examine the deposit
spectroscopically. Thallium gives, when heated in a Bunsen flame, a
magnificent green line, the centre of which corresponds with wave
length 534·9; a second green line, the centre of which coincides
with W.L. 568, may also be distinguished.

4. ALUMINIUM.

§ 896. =Aluminium and its Salts.=--A strong solution of acetate of alumina has irritant properties, and has given rise to accidents. The term alum, in a chemical sense, is given to a class of bodies of the type of AlKSO₄. Common alum is at the present time ammonia alum, NH₄Al(SO₄)₂ + 12H₂O; when made anhydrous by heat it is known by the name of burnt alum, and possesses caustic properties.

§ 897. =Action of Alum Salts.=--Death or illness has hitherto only taken place from the ingestion of large doses of alum or the acetate, and the symptoms in these cases have been those of an irritant poison; we are, however, indebted to Paul Siem[975] for a research on the absorbed substance, in which the local effects as far as possible have been reduced.

[975] _Ueber die Wirkungen des Aluminiums u. Berylliums, Inaug. Diss._, Dorpat, 1886; Schmidt’s _Jahrbuch_, vol. ccxi. 128.

Siem’s research was made on frogs, cats, and dogs. For frogs he employed a double salt, consisting of sodic and aluminic lactate, to which he ascribed the formula Al₂(C₃H₅O₃)₃(C₃H₄NaO₃)₃, equal to 15·2 per cent. of Al₂O₃. Twenty to thirty mgrms., administered by subcutaneous injection to frogs, caused death in from ten to twenty-four hours. After the injection there was restlessness, and, ultimately, general paralysis of the central nervous system. The circulation was not affected; the heart was the last to die.

For warm-blooded animals he used the double tartrate of sodium and aluminium. Beginning with a small dose subcutaneously administered, he gradually increased it, and found, under these circumstances, that the lethal dose for rabbits was 0·3 grm. per kilo. of body weight; for dogs 0·25 grm., and for cats 0·25 to 0·28 grm.; if, however, a single dose was administered, then cats could be killed by 0·15 grm. per kilo. The symptoms commenced ten to twelve hours after the injection of a large dose, but with a medium dose the symptoms might be delayed for from three to four days, then there was loss of appetite, constipation, emaciation, languor, and a disinclination to move. Vomiting and loss of sensation to pain followed, the power of swallowing even saliva was lost, and a condition supervened similar to bulbar paralysis. However true this picture may be when large doses are given subcutaneously, it does not follow that hydrate of alumina in small doses, given by the mouth, mixed with food, produces any symptoms whatever.

Alum baking-powders, containing from 30 to 40 per cent. of alum mixed with carbonate of soda, are in commerce, and have been for a long time, many tons being sold yearly. When water is added to such powders decomposition takes place, the result being sodic sulphate and aluminic hydrate, carbonic acid being given off. Were the hydrate, in small doses, capable of producing indigestion or disease of the central nervous system, it seems astonishing that, considering the enormous number of persons who use alum baking-powders, there should not be some definite evidence of its effect. The author and his family for months together have used alum baking-powders without any apparent injury, and there is little doubt that alumina hydrate passes out of the system mainly by the bowel, without being absorbed to any great extent. In a trial with regard to an alum baking-powder at Pontypridd (1893), the prosecution advanced the theory, and supported it by eminent scientific opinion, that aluminium hydrate was dissolved by the hydrochloric acid of the gastric juice, forming chloride of aluminium, some of which might be absorbed and enter the circulation; that which was not absorbed in the stomach passed on, and, meeting the alkaline fluids of the intestines, was again separated as aluminium hydrate, and as such absorbed.

If this does occur, still there is no direct evidence of its toxic influence in the small quantities used in baking-powder. It may be pointed out, also, that with regard to the possible lethal effect of a non-corrosive salt of alum, presuming that the lethal dose for man is the same as that for a cat, the amount of alumina to kill a 68-kilogramme man would have to be equal to 17 grms., or about 3 ozs. of ammonia alum. This important question can only be settled by careful feeding of animals carried on for a long period of time.

§ 898. =Post-mortem Appearances.=--In the few cases in which persons have been killed by large doses of alum or its salts there have been found corrosion of the mouth, throat, and stomach, and hyperæmia of the kidneys and intestine. In the animals experimented upon by Paul Siem, hyperæmia of the intestine, fatty degeneration of the liver and hyaline degeneration of the kidneys were the chief changes noted.

§ 899. =Detection of Alumina.=--In all operations for the detection of alumina, glass and porcelain vessels are to be avoided. The substances should be burned to an ash in a platinum dish, the ash treated with hydrochloric acid, the acid driven off by heat, and a few drops of nitric acid added, and dissolved in hydrochloric acid, and the solution boiled and filtered. If organs of the body are operated upon, iron and phosphoric acid will be present in the ash; this will, indeed, be the case with most organic substances. The filtered solution is boiled, and, while boiling, poured into a strong solution of sodic hydrate contained in a silver or platinum dish; the iron will now separate as oxide, and can be filtered off. To the filtrate is added a little sodic phosphate; it is then feebly acidified with hydrochloric acid, and ammonia added just sufficient to render it alkaline; a light whitish cloud of alumina phosphate, should alumina be present, is thrown down, and can be collected, thoroughly washed, dried, ignited, and weighed as alumina phosphate.[976] The alumina phosphate is then fused with sodic sulphate in a platinum dish or crucible, and the fused mass treated with hot water; the sodic phosphate dissolves, and the alumina oxide may be filtered off and dissolved in a little hydrochloric acid or sulphuric acid.

[976] One part of al. phosphate is equal to 0·42 Al₂O₃, 3·733 ammonia alum, and 4·481 potash alum.

A solution thus prepared has the following properties:--

Ammonium sulphide; white precipitate of hydroxide.

Potash or soda; white precipitate, soluble in excess.

Ammonia; white precipitate, only slightly soluble in excess.

There is also a blowpipe-test: if a little of the hydroxide be collected, moistened with cobalt nitrate, and heated on charcoal by the oxidising flame, alumina, under these circumstances, becomes of a blue colour.

5. URANIUM.

§ 900. =Uranium.=--The salts of uranium are intensely poisonous. The
nitrate of uranium is used in photography and the arts, and is a
common reagent in chemical laboratories.

According to Kowalewsky,[977] the acetate of uranium possesses an
unusual power of uniting with albumin; the other soluble uranium
salts act also in a similar way. Hence concentrated solutions of
uranium salts corrode the mucous membranes, transforming, for
example, the walls of the stomach into a dead uranic albuminate. If
a non-corrosive salt of uranium is injected subcutaneously,
glycosuria is produced, with fatty degeneration of the walls of the
blood-vessels, and fatty changes in the kidneys, liver, &c. The
animal wastes and ultimately dies; 0·5 to 2·0 mgrms. of UO₃ per
kilogrm. will kill a cat, dog, or rabbit, if injected
subcutaneously. The nitrate or acetate, when given by the mouth,
produces gastro-enteritis and nephritis, with hæmorrhages in the
substance of the kidney. Uranium is not used in medicine.

[977] _Ztschr. f. Anal. Chemie_, xxiv., 1885, p. 551.

§ 901. =Detection and Estimation of Uranium.=--Uranium forms uranous
and uranic salts. Both classes of salts are not precipitated by SH₂,
but are precipitable by ammonium sulphide, and, therefore, in
toxicological analyses are likely to be met with in conjunction with
iron.

The sulphides of iron and uranium may be dissolved in strong
hydrochloric acid, boiled to expel SH₂, and the solution then
oxidised with a little nitric acid; the solution is now alkalised
with ammonium carbonate, which precipitates the iron as oxide and
leaves the uranium in solution. On now acidifying with nitric acid
in slight excess, a solution of sodic phosphate will precipitate
uranium phosphate as a white precipitate, alkalies will give a
yellow precipitate, alkaline carbonates a yellow precipitate soluble
in excess. Barium carbonate also gives a precipitate, and is useful
in separations. Uranium oxide gives a green glass in the oxidising
flame with borax or with sodic metaphosphate.

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. (½ 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.