INORGANIC POISONS.

BY C. E. PELLEW, E.M.

INTRODUCTION.

Definition of a Poison.-Before entering upon the main subject, it is proper to state what must be understood by the term "poison." As a rule this name is given to different substances which, when taken into the healthy human body in quantities not unusually large, produce, as a general result, injurious or even fatal effects. These effects are, as a rule, due to the chemical, not the mechanical, action of the substance, although it is not uncommon to include in the list broken glass, which in some parts of the world is not infrequently used as a slow, subtle, irritant poison.

It must be remembered, however, that almost all medicines when taken in excess will give poisonous symptoms, and, in like manner, many, if not most, of the commonest poisons are in general use, in small quantities, as medicines. Accordingly, the classification of any drug as a poison depends, after all, upon whether it has so far caused a sufficient number of dangerous or fatal results.

Again, a true poison will be active against the normal healthy body. In various diseases, perfectly harmless articles of diet may prove distinctly injurious and set up characteristic symptoms; while every now and then perfectly healthy people are met with who are affected by doses of common drugs, and by simple kinds of food. Thus the evil effects of sugar in diabetes, and of alcohol in genito-urinary diseases, are well. known even to the laity; while cases of idiosyncrasy have been frequently described, where a saucer of oatmeal or a single strawberry have produced poisonous symptoms.

The effects of a poison will vary very much according to the size and condition of the dose, the state of the system, the method of administration, and many other conditions. As a rule, though not quite invariably, it will produce injury no matter how it is introduced into the body, whether by the stomach, lungs, skin, mucous membranes, wounds, or any other way. Occasionally, however, a drug is met with, like curari, for instance, which is comparatively harmless when taken in the stomach, though exceedingly powerful when directly introduced into the blood.

The effects of the various poisons differ greatly among one another. Many of the mineral poisons here dealt with have a distinctly irritating, if not corrosive, effect upon the tissues with which they are brought in contact. As good examples of these we may mention the fixed alkalies and the mineral acids.

In most cases, however, besides the local effects of the poison, there are other specific effects produced in various parts of the system by the poison, after it has been absorbed into the circulation. These may be inflammatory changes in various organs, the liver, kidneys, heart, etc., as from phosphorus; or in the stomach and intestines, as, for instance, in ordinary cases of arsenic poisoning; or a distinct paralysis, partial or complete, of the great centers in the medulla, as in poisoning by bromides, by large and soluble doses of arsenic, by ammonia and nitric acid vapor, and the like; or a slower and gradual paralysis of the peripheral nerves, as in chronic lead and arsenic cases; or some direct change produced in the blood, as by potassic chlorate and carbonic oxide. Besides these there may be marked disturbances of the brain and spinal cord, principally produced by the alkaloids and kindred principles.

To properly classify the mineral poisons according to their effects would be a difficult and complicated task. Hence, in the following pages they are taken up, one after the other, in a rough and simple classification, somewhat according to their physical and chemical properties. The first section will treat of the alkalies; then will come the acids, the halogens and haloid salts, and phosphorus. Next I shall discuss the metallic poisons, beginning with antimony, arsenic, lead, mercury, and copper. And I shall close my treatise with a few words on the metals of less importance.

I. THE ALKALIES AND THEIR SALTS.

The term "alkali" is applied to a substance possessing certain properties. It will dissolve in water, will neutralize acids, will turn red litmus-paper blue, will saponify soaps, will have a "soapy" taste, and, when strong, will corrode many organic substances, including the skin and many of the tissues.

These properties are possessed by the hydrates, carbonates, and phosphates of the common alkaline metals, sodium, potassium, and ammonium, and also of the rarer metals lithium, cæsium, and rubidium. They are possessed by the hydrates of the alkaline-earthy metals, calcium, magnesium, barium, and strontium, but only to a slight extent.

The most powerful of these compounds are the caustic or hydrated alkalies, i.e., the hydrates of sodium, potassium, and ammonium. The carbonated alkalies, i.e., the carbonates of these same metals, while less active than the former, can still, especially when impure, act as powerful corrosives when taken internally. The bicarbonates, however, of soda and potash are so mild that their solutions can be applied in large quantities, as antidotes to acids, not only upon the skin, but also internally, and upon delicate surfaces such as the face and eyes.

Soda and Potash.

These compounds, which are practically similar in their reactions and effects, are met with, as a rule, in the form of sodium and potassium carbonates mixed with some of the caustic alkali.

They are in common use, both in the arts and in the household, for the manufacture of soap, and the preparation of other sodium and potas

sium compounds. And yet cases of poisoning by their means are extremely rare, and usually are the result of accident.

Symptoms. When the solutions are concentrated the victim feels at once an acrid, burning taste, which is usually enough to make him try and spit the liquid out, and to wash out his mouth as well as he can. If the solution is actually swallowed, there is a burning sensation in the throat, reaching down to the stomach. This is usually followed by intense pain, and by vomiting, first of mucus and then of blood. The lips, tongue, and pharynx become swollen, raw, and inflamed; the voice becomes husky, and there is much difficulty in swallowing.

This is generally accompanied by symptoms of severe shock. The skin becomes cold and clammy, the pulse feeble, and the patient becomes extremely weak and exhausted, sinking often into a comatose state. Death may result from this in the course of a few hours, but the patient often recovers from this only to suffer from stricture of the œsophagus and consequent inability to swallow food, or from ulcerations of the stomach, or stricture of the duodenum, which prevent the food from being digested. In either of these cases the patient may linger on for weeks, months, or even years, only to die a miserable death from starvation.

An example of this is given by Dr. Hadden (Trans. London Pathol. Soc., 1890, vol. xli., p. 86), where a stoker on board ship swallowed, for suicidal purposes, several ounces of caustic potash. When seen a few days after, his mouth and pharynx were much swollen and charred, and the patient was suffering greatly. At the end of a week a cast of the œsophagus was found protruding from his mouth, and when carefully removed it proved to consist of the mucous and submucous coats of the whole œsophagus and the larynx, carrying with it some of the circular muscular fibers.

The patient lingered for some time, but constriction began to take place, and more and more difficulty was experienced in swallowing, until the poor fellow finally died at the end of three months.

Post-mortem Appearance.-When death has occurred in a few days, the mouth, œsophagus, and stomach will all show extensive signs of corrosion. The mucous membranes will be much abraded and bloody, and the exposed surfaces raw, and often colored yellow or brown.

When the patient has died from the secondary effects of the poison, the mouth and upper part of the throat may have healed, but signs of ulceration or of thickening and constriction will be noticed in the œsophagus and stomach, or in the small intestine.

Fatal Dose. The smallest fatal dose on record is given by Taylor in the case of a young lady, who died seven weeks after taking one and a half ounces of the common potash solution of the shops, containing some thirty or thirty-five grains of caustic alkali. In other cases death has been reported from half an ounce or so of the dry poison.

Time of Death.-Taylor mentions a case of a boy dying in three hours after drinking the poison, and other cases are on record where death occurred, from shock, within twenty-four hours. The patient, however, may linger for a long time, two or three cases being known where death occurred after two years, and one case, quoted by Wormley from Sir C. Bell, where the patient died after twenty years.

Treatment. Where the poison has been swallowed for some minutes antidotes will have but little effect. The alkali should be neutralized as

far as possible with diluted vinegar, or weak organic acids, or by lemon, lime, or orange juice. Some good can also be done by giving milk, barley-water, solutions of albumen or gum, and the like, and also by giving olive-oil in some quantities, to soothe the inflamed surfaces, and also, perhaps, to saponify any free alkali remaining. It is dangerous to use the stomach-pump where the oesophagus is likely to be so corroded, for fear of perforation.

Chemical Analysis.-The presence of alkalies can be best told by the soapy taste and the reaction with litmus or other test-paper. The carbonated alkalies can be distinguished from the caustic by effervescing with acids, and from the bicarbonates by at once giving a white precipitate with magnesic sulphate.

To distinguish potash from soda we can use four different tests:

(a) A moderately strong solution of potash or its salts is precipitated by a solution of platinic chloride, forming yellow octahedral crystals of potassic platinic chloride. A precisely similar compound is produced by solutions of ammonia, so, if the latter be present, it must be removed by boiling with calcic hydrate, or by evaporating to dryness and igniting at a dull red heat, before making the test.

(b) If a rather strong solution of potash or its salts is added to a strong solution of tartaric acid, or, better, of acid sodic tartrate formed by adding a little soda to the acid, it will form a white crystalline precipitate of cream of tartar. This is soluble in free mineral acids, and also in the free alkalies.

(c) When alkali solutions are carefully neutralized with dilute nitric acid and then allowed to crystallize on glass slides, the potassium nitrate will form long, slender, fluted prisms. The sodium nitrate, however, crystallizes in rhombic plates.

(d) When a drop of alkali solution upon a platinum wire is heated in a Bunsen flame the yellow flame of sodium will always be present. If, however, we place in front of the flame a piece of cobalt blue glass, it is possible, if potash is present, to distinguish its characteristic violet flame. It is more accurate, however, to make this test before a spectroscope, and to recognize the potassium by its two lines, one red and the other blue.

Ammonia.

The alkaline salts of ammonium differ from those of potassium and sodium by being volatile and temporary. Caustic ammonia, or ammonium hydrate, is simply a solution of the ammonia gas (NH) in water, and on heating or evaporation the gas disappears, and with it the alkaline properties. Ammonium carbonate is a solid which dissolves freely in water, but this too is volatile in the air, when dry, at ordinary temperatures, and is readily driven from its solution by heat.

Accordingly, in poisoning by ammonia the patient, if he survives a short time, is more apt to recover and escape permanent injury than in the case of soda and potash. But, on the other hand, the gas itself is poisonous, and liable to cause death suddenly, when inhaled, not only from its caustic effect upon the air-passages and lungs, but also from its action on the central nervous system, causing, when concentrated, a paralysis of circulation and respiration.