Читать книгу Treatise on Poisons - Robert Sir Christison - Страница 39

To these remarks on iodine a few observations may be added on the iodide of potassium, one of its compounds, which is now generally substituted in medicine for the simple substance. The tests and actions of this poison have been examined by M. Devergie; and more lately its medico-legal chemistry has been investigated by Dr. O’Shaughnessey and Professor Orfila.

It is sold in the shops of various degrees of purity. Pure iodide of potassium is in white crystals, tending to the cubical form, permanent in the air, possessing a faint peculiar odour, and easily soluble in both water and rectified spirit. Another variety has the same form, but possesses an odour of iodine, is often yellowish in colour, and deliquesces slightly in moist air. This contains an excess of iodine, but may be otherwise pure. A third variety is impure. It presents less tendency to assume a crystalline form, is more or less deliquescent, dissolves but partially in alcohol, and when dissolved effervesces with acids. The principal ingredient in this article is carbonate of potass; and sometimes the proportion of iodide is inconsiderable. In one specimen I procured 74·5 per cent. of carbonate of potass, 16 of water, and only 9·5 of iodide of potassium.

In the solid state the iodide of potassium may be known by the effect of strong sulphuric or nitric acid, which turns it brown with effervescence, and when aided by heat disengages violet fumes of iodine.

In solution many tests will detect it, such as chlorine, nitric acid, corrosive sublimate, acetate of lead, protonitrate of mercury, muriate of platinum, and starch with chlorine or nitric acid. Chlorine or nitric acid forms a brown or orange-coloured solution by disengaging iodine. Corrosive sublimate forms a fine carmine-red precipitate, the biniodide of mercury; acetate of lead a fine yellow precipitate, the iodide of lead; protonitrate of mercury a yellow protiodide of mercury, which gradually fades into a dirty brown. Solution of starch, followed by chlorine in solution or in vapour, strikes a deep blue colour, which, if the fluid is sufficiently diluted, disappears on boiling, reappears on sudden cooling, and is permanently removed by a stream of sulphuretted hydrogen gases. Of these tests the most characteristic is starch with chlorine; and it is also extremely delicate. Too much chlorine however bleaches the blue colour away.

In compound mixtures most and sometimes all of these tests are useless. If the mixture is deeply coloured, none will act characteristically. If carbonate of potass be present in such proportion as is often met with in the shops, the tests cannot be trusted to.

Process for Compound Mixtures.—The following method of analysis is applicable to all mixtures, organic and inorganic. Add water, if necessary, and filter; and if the fluid which passes through is tolerably free from colour, test a little of it with solution of starch and chlorine. If the colour is too deep to admit of this trial, or the test on trial does not act, unite the fluid and solid parts and transmit sulphuretted hydrogen to convert any free iodine into hydriodic acid. Drive off the excess of gas, supersaturate with a considerable excess of potass, filter, and evaporate to dryness. Char the residue at a low red heat in a covered crucible; pulverize the charcoaly mass, and exhaust with water. This solution will probably act characteristically with starch and chlorine; but on the whole it is better in the first instance to remove some of the salts by evaporating to dryness, and exhausting the residuum with alcohol. The alcoholic solution contains the hydriodate of potass, with some other salts; and on being evaporated to dryness, a residuum is left, on which, when dissolved in water, the starch and chlorine will act characteristically. No other test is necessary; and frequently no other test will act, on account of co-existing salts.

I have found that a grain of iodide of potassium may thus be easily detected in six ounces of urine, which must be considered a very complicated fluid. In the solution ultimately procured nitrous acid struck a pale brown tint, and on the addition of solution of starch a dark-blue precipitate was formed; which, after being sufficiently diluted, disappeared under ebullition, leaving a colourless fluid. On cooling, no change took place; but on the subsequent addition of a drop of sulphuric acid, the blue colour and precipitation were immediately restored. No other reagent acted characteristically, although there was a sufficient quantity of solution to try the starch test ten times at least.

Dr. O’Shaughnessey has proposed a more complex method by precipitation with chloride of platinum.^[357] Professor Orfila says it is sufficient to boil and filter the suspected matter, and to heat first the liquid and then the solid part with solution of chloride, when violet vapours of iodine are disengaged, which may be condensed and subjected to various tests.^[358] I have not compared this method with the one I have been in the practice of using; but, notwithstanding the strong assurances of its proposer, its superiority in point of delicacy seems dubious, although no one can deny its simplicity.^[359]

Action and Symptoms in Man.—From the experiments of Devergie on animals, iodide of potassium seems to be in large doses an irritant, though not a powerful one. Two drachms in an ounce of water killed a dog in three days with violent vomiting, and signs of irritation were found in the stomach, namely, black extravasated spots and ulcers in the middle of them. A solution injected into the cellular tissue caused only local inflammation. Injected into the jugular vein in the dose of four grains, it produced tetanus and death in a minute and a half.^[360] The latter investigations of Dr. Cogswell confirm essentially these results.

Discrepant accounts have been given of the effects of iodide of potassium on man. When first introduced into medicine, it was conceived to be an active poison, not much inferior to iodine itself. Many however have since had an opportunity of observing that it is in general by no means so energetic. Its medicinal doses were gradually raised from one grain to five, ten, twenty grains; and at last Dr. Elliotson gave to not a few patients so much as two, four, or even six drachms daily in divided doses, without observing any remarkable effect.^[361] These and other similar observations however were made at a period when the salt used in British practice was much adulterated, often indeed containing eighty or ninety per cent. of impurity; at the same time it does appear that large doses of a pure salt have been occasionally taken with impunity. On the other hand it has evidently in some instances acted with great force. Mr. Alfred Taylor mentions a case, on the authority of Mr. Ericksen, where five grains produced alarming dyspnœa, attended with inflammation of the nostrils and conjunctiva of the eyes.^[362] An instance has been published where twelve grains in four doses occasioned shivering, vomiting, purging, general fever, and extreme prostration; and the purging continued for some days.^[363] Dr. Moore Neligan informs me he met with the case of an elderly lady in 1841, who, on taking three five-grain doses for two days, while labouring under irregular gout, was seized with severe headache, thirst, and swelling of the face; which symptoms were succeeded in two days by swelling of the tongue, ulceration of the gums, and profuse salivation for a week. Dr. Lawrie says he has known two grains and a half given thrice in one day, followed by great dyspnœa and irritation in the throat; and is even inclined to think that death resulted on two occasions from repeated medicinal doses.^[364] It would farther appear from some important researches made in France, that the protracted use of iodide of potassium in small doses with the food may produce serious derangement of the health,—swelling of the face, headache, urgent thirst, inflammation of the throat, violent colic pains, and frequently bloody diarrhœa. A disease characterized by the symptoms now described appeared repeatedly as an epidemic a few years ago in various parts of France, and spread so widely in one parish, that not less than a sixth of the whole population were attacked. After several careful investigations, it seems to have been fully proved that the affection was owing to the use of salt fraudulently adulterated with an impure salt, obtained from kelp after the separation of carbonate of soda, and consequently impregnated with an appreciable proportion of hydriodate of potass.^[365]

It is difficult to arrive at any satisfactory conclusions from these statements as to the nature and energy of the action of this salt as a poison. But on the whole it appears to be not in general very active; and the few instances of unusual activity which have occurred may probably be put to the account of idiosyncrasy. The most remarkable of its idiosyncratic effects from medicinal doses are salivation, and a series of symptoms which imitate sometimes catarrh, and sometimes a cold in the head. I do not know any facts to warrant the general statement of M. Devergie that 18 or 30 grains may constitute a fatal dose.^[366] The present question is far from being unimportant in a medico-legal point of view. Mr. A. Taylor mentions the heads of a case, very dubious however in its nature, where it was suspected that a single dose of six grains of iodide of potassium had been the occasion of death.^[367]

It is important to remember in medico-legal researches, that iodide of potassium may be detected in the blood, liver, spleen, muscles, urine, and other textures and secretions; and especially that it may be found in the urine, when it may no longer exist in the alimentary canal or in vomited matters. These interesting facts have been clearly proved by the researches of Wöhler,^[368] Stehberger,^[369] O’Shaughnessey,^[370] and Dr. Cogswell.^[371]

Of Poisoning with Bromine.—This singular substance is not an object of much interest in relation to medical jurisprudence, because it is rare, and only to be met with in the laboratory of the chemist. Hence, although it appears to be a poison of some activity, it scarcely requires to be dwelt on particularly.

It is easily known from all other substances by its fluidity, its great density, which is thrice as great as that of water, its reddish-brown colour by reflected, and blood-red colour by transmitted light, the orange fumes which occupy the upper part of a bottle partly filled with it, and its intensely acrid suffocating vapour, which is so irritating that an incautious inhalation is followed by all the phenomena of severe coryza and catarrh. Its odour, however, apart from its acridity, is very far from being so disagreeable as its discoverer in naming it seems to have imagined. In its properties it bears a close resemblance to chlorine and iodine.

The toxicological effects and medico-legal relations of bromine have been examined by M. Barthez,^[372] Dr. Butske,^[373] Dr. Dieffenbach,^[374] and Dr. M. Glover.^[375]

M. Barthez has given the following process for detecting bromine in compound mixtures, such as the contents of the stomach or vomited matter. First separate the fluid matter by filtration, and subject it to the action of chlorine, which will produce a fine orange colour. Should this effect not result, or the change of colour be observed by the deep tint of the fluid, treat the solid matter with solution of caustic potass; filter and add what passes through to the former fluid; evaporate to dryness and char by a red heat; act on the residue with distilled water. The solution contains the bromide of potassium, and is therefore turned orange-red by chlorine. The orange tint, whether struck at once in the fluid part of the mixture, or after carbonization and solution of the residue, is removed by agitation with ether; and the etherial solution of bromine in its turn loses colour when treated with solution of caustic potass, hydro-bromate of potass being again formed.

M. Barthez found, that a solution of twelve grains injected into the jugular vein of a dog, sometimes occasioned immediate tetanus and death; and that the heart was gorged with clotted blood. Sometimes however even seventeen drops did not prove fatal, but produced merely restlessness, difficult breathing, dilated pupil, frequency of the pulse, and sneezing. Dieffenbach remarked similar effects in the rabbit: The animal either died immediately, or soon recovered altogether. In a cat, after the injection of twelve drops of a concentrated solution into its jugular vein, death took place in fifteen minutes; but in another from which a little blood was drawn after the symptoms were fully formed, complete recovery gradually ensued. Butske found a horse suffer so much from mortal prostration immediately after five grains dissolved in two ounces of water were injected into its jugular vein, that he supposed it was about to die; but it quickly revived, and ultimately got quite well. Dr. Glover obtained similar results. When recovery took place, the leading symptoms were panting, sneezing, discharge from the nostrils, rigors and debility.

When introduced into the stomach of dogs, M. Barthez found that twenty drops on a full stomach had no particular effect; that thirty drops occasioned vomiting, and temporary acceleration of the pulse and breathing; and that from forty to sixty drops on an empty stomach brought on violent vomiting, sneezing, cough, dilated pupil and prostration, succeeded in a few hours by languor without any other symptom, and by death in four or five days. In the dead body he remarked numerous little ulcers of the villous coat, some of which had an ash-gray appearance at the bottom, while others were covered with a black slough, easily removed by friction. When the gullet was tied to prevent vomiting, less doses proved more quickly fatal. He likewise observed that the matter vomited in these experiments, even a few minutes after the administration of the poison, had no appearance or odour of bromine; whence it is reasonable to conclude, that, as in the instance of iodine, a chemical change takes place with the aid of certain vital operations, so that the bromine becomes hydrobromic acid.—The experiments of Dr. Butske assign to it more activity as a poison than those now related. For he found that a dog died in a day from taking only five grains dissolved in two ounces of water; and the symptoms were laborious breathing, loud cries, and convulsions. In the dead body he found the stomach internally chequered with bloody extravasation, and filled with bloody mucus, the duodenal mucous membrane universally injected, but the rest of the alimentary canal in a healthy state.—Dr. Glover remarked in such cases, besides the usual symptoms of an irritant action on the stomach, coryza, sneezing, salivation and difficult breathing. Sixty minims killed a cat in seventeen minutes, two fluid drachms a dog in five hours and a half, ten grains a rabbit in five minutes. A dog twice got twenty grains in solution and recovered, but died after a third dose of the same amount. Another got twenty grains in solution every two or three days for a month without injury. In some of these experiments hydrobromic acid was detected in the blood and urine.

Little is yet known of the effects of bromine on man. Butske found that a drop and a half in half an ounce of water produced a sense of heat in the mouth, gullet, and stomach, and subsequently colic pains; and that two drops and a half in an ounce of mucilage excited, in addition to the preceding symptoms, great nausea, hiccup, and increased secretion of mucus. On the other hand M. Fournet, who gave doses gradually increasing from two to sixty drops daily for many weeks, observed that the lowest doses excited itching in the hands and feet, and sometimes colic; that an increase in the quantity caused heat in the chest and nausea; and that forty-five drops occasioned also severe burning and sense of acidity in the stomach, which however were temporary. The appetite was in general rather improved, and the body became more plump.^[376]—Bromine appears on the whole to be a pure local irritant. It acts most energetically when most thoroughly dissolved in water.

Hydrobromic acid seems from the experiments of Dr. Glover to be a pure irritant and corrosive, allied in action and energy to hydrochloric acid. The same experimentalist found that bromine of potassium in the dose of forty grains had sometimes little or no effect on dogs when injected into the blood-vessels, while in other instances less doses cause speedy death by paralysing the heart. Barthez observed that half a drachm in solution produced dulness and depression in dogs, but no other bad effect; and that two drachms retained in the stomach by tying the gullet occasioned death in three days with symptoms of irritant poisoning. M. Maillet observed that two ounces of this salt in the form of ointment, administered to a dog by rubbing it over his nose, and letting him lick it off and swallow it, had no effect whatever.^[377]